Best Tube Amp for High Sensitivity Speakers: 45, PX25, or 300B?

I am looking to change / upgrade my tube amp.  I have a good, all-purpose Primaluna EVO 400.  It employs the EL34's and has a nice sound, especially in the ultralinear mode. Other components:  streaming from Innuos Zenith MKIII to Lampizator Atlantic DAC.  Everything playing through Daedalus floorstanding speakers with a 96-97dB sensitivity. Currently, my office / listening room is on the small side: 12'L x 16'W x 8' H, but I'm building a new listening room on our farm where I will later upgrade some components to fit a larger room.  Now, here are the tube amp options I am looking at:

Audion Silver Night PX25  8 Watts.  Very popular among some, touting a slightly more balanced, dynamic sound over the 300B.

Swissonor 45 SE  or  Tektron TK One 2A3 / 45 i   The 45 is the low wattage (2.5W) but sweet tone alternative. Considered by many to be one of the most musical out there. Of course, its low power makes it more restrictive, only efficient with high-sensitivity speakers and in more small-to-moderately-sized rooms.  It might be great in my current office but would have to work harder in a larger one later.

300B Integrated Amp, Make / Model not yet determined.  8-10 watts.  Of course, the 300B is making a big comeback and has wonderful characteristics, especially in the midrange and especially with certain genres of music such as acoustic, vocals, jazz, etc.  I heard one opinion from someone with a history of work in sound production, "The 300B is great if you just want to listen to a female vocalist with a guitar." One take on it.

Adherents of the PX25 and 45 tend to regard the 300B as a nice-but-limited cousin. I honestly have no experience with any of these three tubes.  I moved from SS to tube with the PrimaLuna, a well-built amp that I have increasingly felt carries some limitations that other tubes--more focused specifically on higher sensitivity speakers--would open up the sound in the lower frequencies and some tone qualities all around.

Any opinions would be welcome.



I think you're on the right track with SET.  I just sold an amp that could use 45, 50, 2A3, and 300B.  I found the answer was:  whichever I could find the best tubes for.  I ended up using some 300B tubes with 2.5V heaters so I ran them on the 2A3 setting.  You'll see below why I sold it.  I did sell it sooner than I wanted because I found a really good guy who really wanted it.  I'm always happy to see my stuff go to someone who really likes it.

Decware has a new 300b that looks very interesting.  There is a 2 yr wait but you might find one on the secondary market.  There is a very interesting thread called "300B lovers" ongoing that discusses some very good design points including the benefits of driving the 300B with something larger than a 6SN7.  Very good reading.

I'm having a custom amp built, very near delivery, that uses the AD1 tube by EML and it is very,very special.  If money is no object I can hook you up with my builder.


Thanks Jerry.  Appreciate the advice.  Looks like you are heading in an interesting direction with the AD1 tube!  Would love to hear your review of it after you've had it for six months.  I do have a budget; wish it wasn't so.  Yes, I've looked at the new Decware 300B.  I'm sure it is a wonderfully designed and built 300B, esp. as an integrated.  I am still debating the strengths and weaknesses of it compared to the other two tubes I mentioned.  It would be an easy default if 300B is the final choice.  Thanks.


Have you considered Lab12 Integre 4 MKII?

Uses 4 KT170s. I love it so much and IMO as good as the much more expensive Jadis I70. Incredibly realistic timbre and bass quality. Vocals sound heavenly. I have one paired with Lab12 Dac1 Reference simply have no more desire to upgrade my DAC and Amp. 

Make sure you get the MKII version that comes with KT170s. The original uses KT150s. I actually tried my MKII with KT150s as well and vastly preferred KT170. KT170 sounds fuller, more holographic, and have slightly softer edge compared to KT150. 

Two of my friends have speakers with similar efficiencies. Coincidently both have 8 wpc.

Listening, very nice except I think they are both under-powered for instantaneous peaks, strong bass

Does someone make a bridgeable version, get two, use as monoblocks, get 16 wpc?   


auroravengeance:  The Lab12 looks nice.  I wouldn't know how the sound and dynamics compare with the three tubes I have mentioned.  Would love more input about the KT170's in the context of the others. Looks very nice and good price.


@gregjacob I have not heard the tubes you mentioned, but I compared the Lab12 against some really good SS amps in 5 digits range like Esoteric Class A, Gryphon 300, Vitus Integrated and Aavik I-280.

I would say it has similar sound and refinement as Aavik I-280. Everything just sounds coherent and correct. It leans towards bright tonality with just a touch of warmth. With KT150s it sounds more aggressive and less warm, perhaps better for rock and metal, but I preferred KT170s for vocals by a mile. 


elliottbnewcombjr:  That would probably be the best way to go. However, I do know there are quite a few 300B mono blocks, but I've not seen a single example of the 45 and PX25 doing the same.  Those tubes get such high marks, it would seem like a good path, but I'm not an engineer.  The tube amp systems that run in the tens of thousands never employ them... There must be a reason.  I do know that some of these run hot, but that's speculation.

This thread has gone away from the low power SET which the OP asked about.  His speakers will be fine with 2 wpc or even 1.8 which is the normal output from a 45 SET.

I'm driving my 96dB speakers with 2 wpc and while I listen at moderate volumes, I watch movies at theatre level and I'm driving the fron speakers during movies with the 2 wpc amp.

Many of the suggestions in this thread are the push/pull design that he is trying to get away from in the Primaluna.  These higher power tube amps are needed for those people trying to use tube amps with the currently ubiquitous 88-92 dB sensitive speakers.


Does it really matter though if the tube amp is low power SET or push/pull design as long it sounds good? I would keep an open mind. There are excellent push/pull design just as there are excellent SET design. If budget is not an issue, I would have recommended that the Silbatone SET amps to be considered. They are wonderful as well. I stand by my recommendation of Lab12 Integre 4 MKII, it really equals high-end amps in the $20000+ range. There are also other options like Leben CS-600 and Audio Note Cobra, but I think the Lab12 is the best in its class already. 

Thank you, Jerry.  You've effectively brought it back to the parameters of my original query.  I wanted to find answers to comparing low-watt valve systems and what the community thinks about these different valves.  I reduced the valve listing to three for a reason; I didn't just want everyone to tout their amps.  I already have a nice Swiss-Army valve amp.  I wanted to fine-tune the question to specific, high-end valves that render extraordinary clarity, dimensionality, breathtaking musicality, and live tangibility that the best valves can produce in conditions that can best employ them (high-sensitivity speakers). I lived in Europe (mostly Spain) for twenty years, studied production with the BBC under Queens College Cambridge, loved the British sound, and built a media company in Spain.  When I sold it all to return to the States, I hoped to one day reach that level of vicarious, tangible music listening that would exceed the most memorable moments in my past professional life.  This is my "end-game" system.  I am building a room just for it (as many here have done).  I am not as interested in thundering power as in palpable envelopment. Music takes me places, on journeys. For a special moment, I am with the creators and craftsmen as closely as possible. They are with me. There are special tubes that are sweeter, more sensitive to the nuances of music than others. I'm on that search for the right balance between dynamics, musical depth, and analog believability as many of us are. And like many of my forum compatriots, I don't want to poorly spend my precious investment on frustrating experiments and regrettable explorations.

Before I do that, I would love to consider several things:

#1 independent wired to the listening room. You might already did it! A great step IMO. If you like to go further, make it two. One for analog, and one for digital.

#2 clean power. EMI/RF problems sometimes are real problems for some people.

#3 room treatment. We, I mean, I listen to the room sounds first, then the other things in the system.

#4 like @audioman58 said. I sometimes like listening some classical, big sound stage, huge dynamic, etc. 300b or those 2w/8w amp really can get them there? I tried the "two years waiting" amp, I like it very much. But, some music want more.



Try something different like the 211 tube ,or 845   More then enough power and sound very nice

a dedicated line yes awg 10 if possible , and as I did 4 wire one a common ground 

the other ground a isolated ground in its separate path connected to its own grid to ground more monies but worth it you don’t need to isolate the digital after this .

buy a very good Ethernet switch , depending on your budget the   SW8  only $600

or top of the line  innuos $3700. Depending on your dac and quality of your audio system  what you can afford , the AC outlets buy quality Gold over Copper Furutech  or another name brand ,even Pangea $100 AC outlet very good . And on router for sure a 12v minimum 4 amp Linear Power Supply , any gsrbage wall warts need to go $5 junk noise makers , little green computer sells for $299 and never use stock power cords ,at minimum on the LPS power supply a Pangea Sig MK2  for example  I even put a synergistic purple fuse in the LPS as well as the upgraded Ethernet switch , each one  small but important  improvements ,

and Ethernet cables cannot be low end or your streaming will suffer, this too applies to the USB cable. Everything counts , I am still working on upgrades  last 

your dac , to me as the source how much can you spend $$. Myself semi retired have to save for more expensive items , the T+A 200 dac  I still have a few months to go to save , is imo and many others dacs we have compared it to directly in our multi state audio get together for its $7200 price a true bargain it beats anything under $15 k and more and has HQ player built into the platform to give you the ability to find tune this to your audio system ,to make it better still. 

I think the OP is mistakenly ascribing personality to the 45, 2A3 and 300B valves. What matters more is the circuit design and parts used. I have a 45 SET custom-built by Will Vincent (autospec) on an ST70 chassis that turned out beautiful! Plus a Japanese Sanei SA-560A 2A3 SET made with Tango iron. This I won at an eBay auction from a Japanese seller. It is the quality of the whole amplifier - the gestalt - that elevates the performance rather than the specific tube type!

I like low-powered tube amps of all designs--pushpull, SET and OTL--so I am not so wedded to a particular design.  As jasonbourne71 stated, it is the particular design and parts used that matter most.  In particular, the output transformers and interstate transformers (if used) that matter a lot.  

I do have some tube preferences (meaning I've heard a number of good amps made with a particular tube type), but it is not absolute such that I universally prefer something made with that type of tube over others. 

Of the three small triodes mentioned, I tend to most like the 45 as long as it is used with suitable speakers.  I own a parallel 2a3 amp that I used with 99 db/w efficient speakers and a 45 pushpull amp (both have sufficient power for my purposes, but then again, I don't play the system very loudly.  I currently run a pushpull 349 amp (5.5 watts per channel) that I like a lot.  I tend to prefer the 45, 2a3, 300b over the larger transmitting-tube SET amps (211, 845) although these can sound very good.  For pushpull amps, I also like a number of old and new designs that employ 6L6 and KT66 pentodes.  For really exotic tube types, I like the 350B, 349 (pentodes) and the 252 (triode somewhat like a 300b).

For the OP's 96-97 db/w speakers, it might be possible to use the three triodes mentioned (particularly the 300b), as long as the owner is willing to accept some restriction on very high volume listening.  I personally feel that some compromise in that area is worth it.  For a safer bet on compatibility, something in the 40 watt range should be sufficient.  

Look for a Dennis Had Inspire 300b. He builds each by hand one at a time, essentially made to order.  Sells on ebay under radioman731.  He built me a KT88 last summer, added a volume pot so I can stream directly to the amp, then straight to Klipsch Forte 99dB efficiency or Focal Aria at 92dB.  The KT88 can run 6L6, 5881, EL34, KT77, 6550 and KT88 @8-10 W depending on output tube. Pure heaven with the Klipsch. His 300b comes fit with the new production WE 300b for $4,250 and is rated @6W per channel. I was able to pickup in Cary, NC and he treated me to lunch with an audio buddy, tour of his shop the Toyfactory, plus an afternoon of music and career stories.  BTW, he founded Cary Audio, credentials enough! 

I currently own a Tektron 2A3/45, MastersounD 300B, Art Audio 845 and most recently just sold an Allnic m311 (PX25). I utilize beautiful Coherent Audio 18's that have a similar level of sensitivity @ 98+dB. My listening room is a bit larger, but overall, this question is one that I have experienced directly for many years. But, before I actually post, I want to share that I have been reading blogs for many years, but have never actually commented as I find the audio journey such a unique and personal experience. All I can profess to do is share my own unique and individual direct experiences. 

I love my Tektron 2A3/45. These low powered tubes built by Attilio in Italy are a wonderfully designed and built, very reasonably priced gem. The tubes (2A3 and 45) are to me the epidemy of SET sound. They deliver an open, airy, detailed experience that is intensely close to an intimate live performance. However, and for the record, there always seems to be a however, in some genres of music, they can just lack a complete and full body. For an intimate setting of both female or male vocalists, or even the delicate concert delivered by a cello, I find nothing even compares to these tubes. But, when I play a full orchestral rendition of a moving concerto, or a little rock and roll, they tend to fall slightly short in the arena of complete body and tonality throughout the frequency range. Please don’t mistake full-body with bass. When in a proper setup, this amp has plenty of fast, full lower frequencies which I have never felt lacked bass.

My MastersounD 300B however, is fast, dynamic and never has lacked for power, regardless of the demands placed on it from the style, genre or volume of music. It sounds more truly complete throughout the frequency ranges, but and here we go again, lacks that true SET quality. I know I might be committing audio Hare Kari, but to me, it does not have the detail or the delicacy of the 2A3/45 tubed amps.

The Art Audio (845) maintains more SET true nature than the 300B, albeit, less than the 2A3/45. It actually has a sound closer to my Tektron amp than the MastersounD does. It delivers amazing power with full body and a force that is not touched by either of its rivals. One of the many beauties of the Art Audio Carissa is that it does not overdrive the tubes and therefore does not get any hotter than my 300B tube gets. I know, once again, the comments seem hard to imagine, but when you speak with Art Audio you will understand their reasoning and why the amps do not get hot like most all other 845 amps. But, to me the 845 just lacks a little tonality throughout the dynamic range. Perhaps just a tad rolled off in the highs, especially compared to either the 300B or the 2A3/45 amps. It also loses just a touch of detail and delicacy found in the Tektron; however, it delivers amazing full body force and punch that is spine-tingling during a moving classical overture.

The Allnic m311 (PX25), so sorry, I actually have never heard the Audion PX25, but owned the Allnic for man years. Was a great amp. It delivered more punch, power and body than the 2A3/45, more SET like detail and delicacy than either the 300B or the 845. However, to me just lacked a little excitement. It always sounded good, very good, but rarely if ever stopped me in my tracks and caused that hold your breath pause that comes with music being played through a piece of art.  Still, the Allnic is perhaps one of the finest amps I have ever had the pleasure of owning and a true joy to listen to as a daily driver. However, getting PX25 tubes can be a challenge. KR Audio is the only current manufacturer of these unique tubes and they only produce tubes when backorders are substantial enough to warrant the process.

This week I will be taking delivery on an Art Audio Jota, a high-current set of monos that delivers 20+ watts through a unique 1605 power tube. I am hoping that they deliver the “unicorn” I am seeking; SET like sound with a bit more punch. Until then, I am a spoiled audio aficionado that switches between my 2A3/45 and 845 as the music and my mood demands. What a great hobby we all have!

@gregjacob Something you want to consider before moving ahead blindly with an SET purchase is the difference between sensitivity and efficiency. Sensitivity is a voltage measurement (2.83V @ 1 meter); efficiency is a power measurement (1 Watt @ 1 meter).

If the speaker is 8 Ohms these two are the same since 2.83V into an 8 Ohm load is 1 Watt. Your speakers are a lower impedance than that; hence they are not as efficient as you think they are. You did not mention which Daedalus. If a 6 Ohm model subtract 1.5dB from the sensitivity measurement to arrive at the efficiency. If 4 Ohms subtract 3 dB since 2.83 Volts into 4 Ohms is 2 Watts, not 1, a 3dB difference.

Now the sensitivity measurement came into vogue in the 1970s when solid state amps became really common. Most solid state amps can behave as a 'voltage source', which is to say they can double power as the speaker load is cut in half (although a cheap one may not be able to do this at full power if limited by its power supply). OTOH, tube amps don't do this at all- in particular SETs. For tube amps in general, the efficiency spec is more useful on this account. If a tube amp is able to act as a voltage source, it will employ feedback (SETs usually do not) and will cut power in half as impedance is doubled rather than doubling power as impedance is halved. This makes tube power really expensive.

A further complication is you are talking about an SET. SETs have about 20-25% of usable power. Above that power level, even though they are not clipping, the higher ordered harmonics start to show up in their distortion. The ear uses the higher ordered harmonics to sense sound pressure. The result is they start to sound 'dynamic' since the power used in music is mostly on transients and now you are getting loudness cues on the transients (that are artificially generated)! This is why so many people talk about the 'dynamic' nature of SETs. They are misusing the amplifier by having a speaker that lacks efficiency.

The bottom line here is that unless your room is very small using an SET on your speakers is a Bad Idea. Quite simply you'll need more power. One other thing- SETs have trouble making bandwidth due to output transformer limitations. Effectively this means that to get hifi bandwidth the amp probably should not make over 7-8 Watts. Add to that the problem of usable power and you can see that 2-3 Watt isn't going to make it in most rooms with speakers like yours!! A more powerful SET will lack bandwidth and the typical way of doing that is to compromise bass bandwidth in favor of the higher octaves (IOW its a design consideration the designer has to face).

This does not mean that you have to leave any musicality on the table when going with another kind of amplifier! There are push pull tube amps that have the same kind of 'magic' of SETs and now there are even class D amplifiers about which the same can be said.

FWIW I have speakers that are genuinely 98dB efficient and I find I need at least 40-50 Watts and my room is a bit on the small side. I don't use all that power of course, but it does mean that the amplifier is loafing and as a result distortion is very low- this results in greater transparency (distortion obscures detail just so you know- you do pay a price for higher distortion amps like SETs!). Of course we all want the relaxed liquid mids and highs that SETs are known for but seriously that's no problem for other kinds of amps as I said. And there are those occasions where the system really has to use some power- such as playing the Saint-Seans Organ Symphony at a proper level and doing it without strain.

So if you really don't want to go down a rabbit hole and flushing dollars down the loo at the same time, IMO/IME avoid SETs with your speakers, unless you are in a very small room.

@atmasphere What you said is very valid. Why limit our options just because of some preconceived notions? 

My first time listening to a tube amp was one of the large Line Magnetic. I have always thought tube amps were supposed to sound seductive, sweet, and warm. Imagine my surprise when I was greeted with an aggressive and powerful sound. I then realized whatever I thought about tube amps were not exactly right. 

I've heard the Jadis I70 last year and I absolutely loved it. It had power but also high level of refinement and liquid sounds. The sound was definitely high-end and same quality as the other high-end brands like Aavik and Nagra. It converted me and I realized I had to at least shortlist a few tube amps for my upgrade consideration. 

Aavik Class D integrated are revelatory as well. Those who gave them a listen had their prejudice about Class D completely shattered. 

Aavik Class D integrated are revelatory as well. Those who gave them a listen had their prejudice about Class D completely shattered. 

Yes, a lot of class D amplifiers in the last 20 years were pretty effective at giving class D a bad name. These days there are class D amps that give any tube amp more than a run for its money. I've been playing a set for the last 2 years and don't miss the tubes at all- I have the same organic, liquid mids and highs and plenty of impact in the bass and its actually easier to hear what's going on in the rear of the sound stage. No tradeoffs!

I would purchase an amp that can drive any speaker you may get in the future as well


the line magnetic 805 sounds amazing is built with premium parts is affordable and has enough powerfor most loudspeakers they are well built and smoke prima luna


Daveand Troy

Audio Intellect nj

line magnetic dealer

@redox44 I had a Tektron that had heater voltages for 45, 50, 2A3, and 300B and I loved it.  Sold it to a friend who loves it a lot.  Great amps.


A friend with very sensitive (99db) wide baffle speakers with Beyma AMT tweeters has a Coincident Dragon mono block amps which sound amazing. You might take a look at their site:

Look up Radu Tarta  one of the best tube designers in all North America 

specializing is SET 300 B amplifiers using Lundahl transformers and chokes 

as well as many custom super high quality parts ,built to last a lifetime 

and a Huge cut above his prices are actually less then name brands with far superior build quality .he has built me both Amplifiers and preamps ,

beung in a multi state audio get together ,you can get as custom as you want 

Power coated front and top plate with even pinstriping. If you want That from 

front panel express , not cheap but built to whstever you want and uses the finest Khozmo volume attenuator and input digital read out  A+ quality roughly $5k on up 

and Tubes as much as you want to spend , Western Electric 300b ,Taks from Japan  KR , as I mentioned before your budget dictates the options ,A Giant step up think Bentley Quality for decent name brand priced ,not China !!

For my flea watt system, I chose the 300b because many reviews speak especially fondly about this tube seemingly more than others.  The 300b will be my benchmark to judge other future tube components. 

I can confirm what auditroy mentioned. I have a LM-805ia with all different tubes, 93db efficient Tannoy Turnberrys and a couple REL S/510’s. Good times. I am interested to listen to an Atma-Sphere and the 300B from Decware. I’m told those are supposed to be the next level up in amps from where I’m at in my journey. I hope that whatever you end up with, you have an opportunity to listen to it in your own listening space first.

@audioman58 Thanks for mentioning Radu Tarta at Simple Pleasure Tube Amps. I just spent some time looking at his site and, well, wow. The descriptions of the build indicate (to me, a layperson and to a tech I know who makes amps) a very high level of expertise and care. These small builders are the way to get very high value for reasonable (if still not cheap) costs. But you can look at the parts he uses and know that he's not chintzing on the parts. 

For those curious about the site:

I would like to thank **everyone** for some great entries and advice. I know this website has its detractors but in my year of involvement, it has been a great source and I've meet some amazing people in this community. Since starting this thread, I have been disconnected due to demands and am just now able to respond.  I've read the whole thread and reread it. I want to thank all of those who have added specific suggestions, brands, and models of tube amps that have been yielding good results for you.  There is also a treasure trove of good info you have shared on tube amp science--much of which I am just now beginning to understand.  From the thread so far, I have been immediately influenced by your advice on putting my simplistic goal of the best-fitting amp into a much broader understanding of the tube amp's strengths, weaknesses, and the many alternatives that go beyond what I narrowed my list down to.  Honestly, I am revamping my thinking on what my options might be. My budget does determine what I can consider (as for most of us).  I think I am looking more to "stair-stepping" upward from my current amp (PrimaLuna 400 EVO) to something that provides moderate, reasonable gains without breaking my bank.  I will have a lot more that I can spend in a couple of years when I unload a business.  But for now, I have to settle for only moderate improvements... the best bang for the buck. Again, thank you for your participation.  Hopefully, many are reading this thread and gleaning from it as well.  👍

This has been a most informative thread. As I'm waiting patiently for my Decware amp,other people's experience and knowledge is of great value. The simple pleasure tube amps site is really impressive, thanks for sharing that.

gregjacob OP

It is a great thread, so much info from others.

I needed 16 ohm taps, so I had limited choices. I have extremely efficient horns/15" woofers, historically happy with 30 wpc, so I never thought about more than 45wpc.

I never considered it when I bought my Cayin A88T, but it may be a good idea, whatever category you go for, to go for a bridgeable model, keeping the option for another in the future.

let us know what you end up choosing.


There is a 300B based OTL amp available in kit form.  If you don't want to build it, announce on the manufacturer's forum that you would like someone to build it for you.  You will have to compensate the builder but it is the best 300B amp money can buy.

Personally, I love my Elekit 8600 300B amp. Even if you get someone to build it for you, the price is fantastic and you won't have to wait nearly as long as you will for a new Decware amp 🤮

I love my Yamamoto 2A3. Hand crafted beauty with soul. Plenty of power with my 96dB speakers. There are 45 and 300B options as well.

Great question - great idea for a thread.

I previously used a vintage (Cary Audio/Dennis Had designed) AES SE-1 300B stereo amp, from the ’90s. It sounded great and I loved it with my 93dB sensitive/efficent/whatever JBL studio monitors.

Then I had a chance to compare it to a pair of Alan Eaton 45 monoblocks, that put out somewhere around 1.5 watts. The Alan Eatons were better - deeper bass, clearer, lovely treble, richer tone, more beautiful sound. Note - this is in my room, with my listening preferences. I typically listen in the near field below 75dB, so I am just using a fraction of a watt. The Alan Eatons are simply coasting.

A couple months ago I also picked up a pair of Altec A7 Magnificents. ~96dB.

I learned about these amps on the Glow in the Dark audio website. I love that website for the photos, the writing, the descriptions of the various amps and tubes.

Also, as I have previously done, I humbling suggest you download a simple app for your smartphone so you can check what volume you normally listen at. I use decibel X-Pro. It was not expensive and works great. I use it frequently. No, it is not the best SPL meter in the world but it will tell you what you need to know.

Personally I think the 45 tube is where it’s at and these simple, simple circuits with minimal parts count and highly efficient speakers.

Your 96dB speaker requires 8+ watts to sound reasonable for full scale music.

If you insist SET using DH tubes,  PX25 or 6336A is the way to go.  paralleled 6336A ( Using both sections of single tube for one channel)  could provide 15W pure class A output with 2 windings of primary per channel.  2A3, 300B, much less 45 has to be used in push-pull fashion to produce enough power for your speaker.

Sound wise, as I posted in "300B lover" thread, 45 is the most balanced DH power triode. However, all the commercially available DH amplifiers not using DH driver tubes have bottleneck at their driving stage, so the amp sounds what driving stage sounds, output power tube sound signature are not most impactful.

The best sounding low power SET amp I built using 71A (shunt regulated) to drive VT25A/801A, producing most seductive 2w pure class A output when driving my JBL horn system.

Hi Gregjacob,

Some nice and great responses to your inquiry on quality flea-watt tube amplification for your efficient speakers. I have had tube amplifiers in the past and for the past 12 years, I am the proud owner of a BorderPatrol S20 parallel 300-B tube amplifier with dual power-supplies. I have heard a few tube amplifiers on my system and all of them sounded good with of course their own sonic signatures, but my mind was made up when I heard the BorderPatrol amp. Not only did this amp sound more dynamic especially in the bass area, but articulation, frequency response and clarity of the music really drew me in to each performance. Also, vocals especially female take on a very realistic presence. With this amp, the music on the whole seemed to have for lack of a better word, more body. I, also own three solid-state Class-A flea-watt amplifiers all of which sound great on my system. While they all have their own sonic signatures, I keep on coming back to my two favorites, the BorderPatrol S20 300-B amp and the First-Watt SIT-2. I wish you well on your tube-amp journey.

Regards... John


I think you're going to have to try some different options in your system. while i appreciate the opinions of those who have a strong technical understanding, my experience is that things that should not work DO work for me in my system. 

Again, my system, my room, my preferences. 

liquidsound  John:  That BorderPatrol is a beautiful unit.  Out of my current budget but could be a bucket list amp one day.  Thanks for sharing.

Markusthenaimnut:  I think you are right.  I failed to give proper disclosure from the beginning of the thread:  exact speaker specifications, exact room dimensions, exact distance to speakers and, finally, average decibel listening of what genres of music.  I know all that could / would affect answers and opinions here.  

At any rate, the wealth of information continues to grow.  Thanks everyone. Your participation is being heard and it's a help to many!

@gregjacob are you looking for an "integrated" amplifier which includes the preamp just like your Prima Luna, or are you looking for just the amplifier? There are much more 300b amplifier offerings than are integrated 300b.


Yes, I was looking for integrated at this stage of the game as it would probably be more within the current budget than separates, cables, etc.  Also, space issues where I have my sound system located.

My goal has been to learn from this system so that a major upgrade in about 2 - 3 years would be sussed out.  We are renovating an old farm in the country. I have a room that I'm renovating to be a dedicated music room, larger than the office where I currently have my system.  In my current room I have limited space with a pair of Daedalus Muse speakers.  They are sweet and demand little and I am not pushing them at all.  I will be upgrading to either a larger set of Daedalus or moving to a pair of Coherent 18's.  Both are reasonably high-sensitivity speakers but might require a different amp system at that time.  I'll have a better budget then as well. 

There is a reason 300 B everything /  anything keeps coming up for sale.

it inherently does not work well in its output application or generally falls way short of the power tube task.


perhaps consider as a driver tube but nothing else 

clhs04:  I believe there's some truth in that. I think most sound systems, environments, and demands do not fit the 300B ability.  Perhaps for the 20k+ 300B amps, there is a window to perform better, but not the low-budget systems.

@clhs04 I do not understand the comment that a 300B falls way short of the Power Tube Task. Likely, if they are not in the right "environment", they will fall short. 

Like the OP I too have the Daedalus Muse Speakers and enjoy them with a pair of Wellborne Labs DRD300 amps with both the silver wire and the Black Gate Cap upgrades. They are about 8 watts. 

Presently using a Modwright LS100 preamp with the MC option in play. My Atmasphere Pre also sounds exceptional in this system with the 300B tubes. 

Either Streaming or Vinyl has plenty of oomph . Jazz, Strings , Classical and limited Classic Rock all sound excellent. No I have not listened to Rap or Heavy Metal so no comment in that regards.

There is plenty of power to listen at all levels of volume in a smaller room. My listening room is 11 x 15. 


Alternately my office, which is 13 x 17  has a 175 watt Class A/B pushing PROAC Response 3.5 and  a 300B tube would certainly not cut the mustard in that system.

Rambling thoughts -

All this talk of "not enough power for your speakers" makes me wonder how loud everybody is listening. I mean really, on a day-in and day-out basis. I seldom get louder than 80dB. Sometimes I go louder, but not as a matter of routine. And I listen to all types of music, including hip-hop, rap, dub, jazz, classical, country, vocals, rock.

I'm seldom using much more than a watt. Ok, perhaps sometimes when I'm listening to the original quads that are in my room, or my 2805s. Or if I feel like cranking up Jimi Hendrix's fist album over the Altec A7s. I might be a little over a watt under those circumstances. But really, how loud do you typically listen? And what kind of speakers are you driving? Something with a power-gobbling complex multi-way crossover? 

8 watts is a lot. 15 watts is a lot

My preference is for simple circuits with a parts list employing high quality (read: fit for purpose) parts. Yes you can build high power amps with complex circuits and some of them can sound very very good. But then you're in a different place. Maybe listening for different things. That's ok. Totally ok. There's no one right way to listen or one "right" set of listening preferences. Those who prefer low power SETs are not "better", "smarter" or wiser than those who prefer amps capable of arc-welding. Same with those who prefer Quads, whatever their vintage. Or Altecs or any of all the myriad options available out there, or push-pull or solid state or whatever.

But I do think it is important to experience some of these options first hand, in a well matched system that can show the technology to good advantage.


There are just too many choices for pure sound in single-ended amps.
I have the following for my JBL 3 way (077/375/130A) and Tannoy GRF memory:
Custom made EL84 SE with 6BA6 driver  
Custom made 45 AMP SET ( convert to using 46 type via adapter ) with type 56 driver/phase splitter
Custom made WE 350A SE with 12ax7 and 6FQ7

Custom 6L6 family single ended with 6AU6  ( similar to 6BA6 )
Custom 2A3 SET with EF37A driver.   
Custom 2A3 SET with 12AT7 interstage
Cary CAD 300B SEI with factory upgrade ( plus I upgraded the coupling caps to the best sounding combination )
Custom 300B with C3g
Custom 300B with 417A interstage
Custom 300B WE91B circcuit
Custom 300B 6SN7 interstage  
For 6SN7, I only recommended vintage Tung sol round plate smoke glass vt231 or 6SN7GT.    Clarity and holographic fine sound is what I prefer.

I have too many amps.
I have top Push-pull amps as well.
EL84, 7408, EL34, 7027...

What it boils down to is matching.


As for integrated, you can't get better than Cary.  This is just my honest opinion.
I sold the Cary to my friend as he was just like you with a strong curiosity about 300B SET.  After I lent him half of a dozen amps on his Altec A5, he truly appreciated the Cary with the WE 300B.
If you don't mind vintage,  the Stromberg Carlson ASR-220 is pretty kick-ass with my DIY Philips/Norelco 12"  AD-5277M full-range driver in a Tannoy Rectangular GRF cabinet ( similar to JBL C34 cabinet )