Cool running, low powered power amp

My regular amp is a Class A, all tube (KT 88’s) affair that runs very warm. For most of the year, it doesn’t matter. But in the dog days of summer, it can become unpleasant in my smallish listening room, where the AC doesn’t reach as well.

My speakers are Volti Razz, which are something like 97 db efficient. My big tube amp is out in California getting repaired, and at the moment, the Volti are enjoying time spent with a Scott 299A. Those 17 wpc are plenty (and sound way better than a 65 year-old amp with original tubes (or at least, tubes marked "H.H. Scott") should. Volti says it only needs to be 8 watts to do the job.

I was thinking of First Watt, or maybe Pass Labs XA 25. But both of those are also Class A. But maybe all Class A are not alike in terms of generating heat. I am not anti-class D, and have had two Class D amps that sounded good, but I’d be more interested in A/B, or cooler running Class A. I'd like to bring it in under $3000, and I am a big fan of used equipment.





With those speakers I'd get something from Decware. My 4 watt Mini Torii doesn't put out much heat at all and nice and loud but not thundering with my 92db de Capos

An XA-25 runs hot. Get a cheap little anything a/b or D to fill in, or spend a little on the AC.

Since you have Class A already why not try something different.

The Benchmark AHB2 is a good choice for very efficient speakers because it is quieter than anything else you may have heard. Some say sterile in sound but I think it is a super clean and smooth sound. I traded my last AHB2 a few days ago and I know I will miss it since there are no other amps I have heard that can do what the AHB2 to can do.

If you want to stay with Class A and also want to save a lot and I mean a lot of money, consider the Schtt Aegir 2. I have the Aegir 1 which is all Class A and I use for my headphones since the 20 watts suffices for that. My prior version can be had for about $500.

I was too late to buy a used First Watt amp for the same use. That cost about $3k. I decided to try the Aegir since it was rumored to be about 80% of the FIrst Watt. It was more than good, and I am happy with it. The Aegir 2 is supposed to eliminate some tiny mechanical noise from the amp.

Benchmark has a 30-day home trial.

Schitt has a 15-day home trial. 

BTW - there is a person is the SF Bay Area selling a KRELL Duo 175XD for a tiny bit more than your max limit. I owned this Class A amp, it does NOT run hot, and it sounds great. Only a local sale though.



Parasound A23+ is under $2k, Class A/AB and has a powerful but warmish sound. Used probably ~$1000-1200. You might end up keeping it. 


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I had the same issue with running tube amps in the summer as yourself. It was resolved with a Class A , Audio Note Soro Integrated amp.

Actually Both the Audio Note Oto ,or Soro tube integrated amps would be possible options for you to consider. 

I live on the top floor of a condominium building where running a tube amp in the summer time was an issue. I would have to switch to a Solid State amp in the summer time.

The Audio Note Soro amp resolved this issue for me and sounds fantastic. It could be different for you considering the AC does not reach that well in your listening room.



You could go out and try something very new to you, such as the Mr Nixie STCII Power Amp.

At 18 Watts, it should easily deliver for the 97dB Speakers.

With the referred to Budget, Bi-Amping is also an Option with plenty of monies remaining.

Thank your for your suggestions! I have checked out each one, going to websites and reading discussions about them. And i entered some new worlds (Such as Mr. Nixie and Decware) that I didn’t know about before. You have got me exploring and thinking, which is what I wanted. I don’t know which way I will go yet, but a few of you did express the spirit of trying something new, and since this is a two-month substitute, I can afford to think outside the same old thing. Of course, that Burmeister looks great, but my retirement budget is a real thing, so reaching that far remains a dream.

And yes, I might buy a small window AC unit and pre-cool the room before I shut it off and listen. After putting so much money into a whole-house AC unit (that works great everywhere but this one carbuncle of a room hanging off the house), it is a bit frustrating that I have to resort to that. A nice cool-running amp might be more fun!

Thanks, all...

+1 BM ahb2.  class H (class A/B w/ voltage rail regulation) with 92% efficiency. Cool running device in a small form factor.  Highly recommended if you are willing to make an invest.  Otherwise, for $660, you could consider Smsl vmv A1 10 watt class A.  

I have the Aleph 2s but in my small room they raise the temp too much, except in the dead of winter.  I swapped in the SMSL VMV A1, a fantastic, 10 watt class A amp that generates no heat compared to the Pass gear.

It'll have you questioning the need for other space heater amps.


Another vote for the Schiit Audio Aegir. Runs very cool and possess amazing sonic attributes without breaking the bank. I also own a Pass Labs Class A amplifier and it definitely substitutes as a room heater.

Decware SE84UFO.  I have one and it pulls like 40 watts of power (less than most SS amps).  it will not heat up your room.  And outperforms many amps I've put it up against that cost several times as much.


Something you could experiment with if it’s feasible for your home is to close off less critical air ducts for your listening sessions. This will give all open vents a boost. Might be all you need and you spent nothing but a minute of your time.

I second the Benchmark AHB2 recommendation. Clean, neutral, and balanced sound. 

Before my current Audio Note Cobra, I used Perreaux 100p which was a really competent performer for its price. 

Other good power amplifier I've heard in this range were ATCP2 and Moon 330A.

But honestly, if you can cough up a few more thousands, just go for a pair of Audion MKIII monoblocks. 

I wanted tubes in my small office, went for a Little Luxman

luxman SQ-N150, 10wpc, delivers more than that, excellent features

$1,950 US Audio Mart

here it is, far left

I use it with my restored AR-2ax (sensitivity 90db). Enough volume for my office, but not for a larger space, however with your efficient speakers, it would be a winner. It has an excellent sounding Phono (either MM or MC), and 3 line in.

One feature I like is the push down power button can stay on, so it turns on/off via my Chase RLC-1 which has remote power, very helpful in my setup,

It has balance, a feature I definitely want in any system.

I find the Benchmark amp everything that has been said about it, in this thread. A third recommendation.

Class D would work well, but I have no experience or recommendations for you.

I can highly recommend the new CODA S5.5, but that is going to be over $6,000, amazing solid state Class A amp that runs only slightly warmish (I can easily hold my hand on the cooling fins even at full tilt).

The wait time on the Coda S5.5 is now up to 4-5 months. I ordered mine March 15 and it's not shipped yet. 

Okay - after all of your good thoughts provoked an examination of my priorities with this summer substitute of an amp, I decided to order the Decware Triode amplifier - all 2.3 watts of it. I decided that since I have speakers that can actually make very good use of that kind of amplifier, and I've never owned anything like it, I may as well lean into the whole thing. These are my first and only set of horn speakers, and to not explore the low-power SET experience seems like a waste. I ordered it today, and do not yet know when it will arrive. 

Thanks again for all of your opinions - I valued them all, including exploring ways to goose my AC in this room.



The Decware is a fantastic choice.  I was just going to suggest it or maybe a Decware Rachel.  Happy listening and be sure to report back on your findings.

Class A is always going to run warm. There's no such thing as a 'cooler running Class A.' They would only be cooler by being lower power.

There are class D amps that sound every bit as good as the best class A tube amps now so no need to deal with the heat...

Class A is always going to run warm. 

Companies like KRELL and Westminster Labs say their amps are Class A and they run cool. The KRELL Duo 175XD that I owned ran cool and sounded like other Class A amps (maybe better). That was up to 175 watts of Class A, when needed. I also own a great Class A amp, the CODA #16 so I have a good frame of reference for the KRELL.

Companies like Gryphon say that the iBias based Class A such as the KRELL are not real Class A. You need to waste electricity for true Class A.

The new KRELL KSA i400 is the next version of what I owned. I expect that to also run cool-ish. That amp is 400 watts Class A at 8 and doubles to 800 and again to 1600. I think it is only 400 watts class A at all impedances.

CODA has a lot of 'fins' and Krell 175xd gets a lot of fans (4) in the back.  Won't you be bothered by them?  

Well - the joke's on me! How naive! I ordered my new Decware Triode, and understood there was a waiting list. I figured it would arrive sometime in July, just when I need it. Well, that may be true, but it would have been three July's from now. As the nice person at Decware said, the waiting list is "at least" three years long. 

I know they are a niche company that makes bespoke products that people apparently love. So, I have no problem with their business plan and respect their approach - I just didn't understand it. So, I canceled my order within hours, and now the search goes on.

Since I am intrigued by low power tube amps at the moment, I see that there is an Eastern Electric Mini Max for sale within my budget, and also a Sophia Electric SET Music Baby amp as well. Anyone have experience with either or both of those?

I do understand that all Class A amps  emit heat - that is baked into the design. But it is a matter of having a 100 watt bulb, or a 15 watt bulb burning in a small closet. I think the 15 watt would be more comfortable.



Yes, the Decware waitlist is something to contend with.  There is a set of UFO monoblocks on USAM right now just above your budget line.  However, the regular UFO's come up about once a month or so for sale.  

There is also a gorgeous, upgraded Rachel for sale that should do everything you want, as well and it's under your budget.  I'd take a serious look at that one.

I would strongly recommend hearing any amp first before buying.  In particular, putting money down for something you have to wait three years for seems very risky.  I've heard three Decware amps and all of them were whimpy sounding things that sounded pleasant, but, very limp and unable to deliver punch.  The speakers they were used with were high efficiency speakers (about as easy or easier to drive than the Volti Razz).  

With low heat a big priority, Class D solid state makes sense.  Find a high quality lower powered Class D amp.  

If you are sticking with tubes, the advice above about Audio Note Oto or Soro is good, if you can find something used in your price range.  I would not be looking at hot running tube amps such a those employing KT88, KT120, KT150 or KT170.  If you have someone to service your amp, you might be able to find something vintage that runs EL84, 6L6 or KT66, and even EL34 (not one of my favorite tube types, but some amps running those tubes sound good).  These tube types I've mentioned tend, to my taste, to sound better than the KT88s you run (not as hard or brittle sounding).  

Good luck in your search.

+1 @fthompson251 I would talk to Aric of Aric Audio about his tube amps. He makes a couple SET amplifiers. 

@dtorc FWIW, we make a 5-Watt/channel class A tube amplifier that can sit on a sheet of notebook paper with room left over. I designed it for my bedroom system.

BTW, something to keep in mind about SETs: if they have no feedback (and most don't), their actual usable power is about 20-25% of their rated power. This is because at power levels above that, the higher ordered harmonics start to show up on musical transients. This causes the amp to sound dynamic (since the ear uses higher ordered harmonics to sense sound pressure) but its really distortion masquerading as 'dynamics' and is the source of why so many people say SETs are a lot more dynamic than their power suggests.

Consider the Schiit Aegir. No, really.

I just swapped a pair of Aegirs for an ARC VT100MkIII and they are no joke. You'd probably only need one. And the resale on Schiit is so good... I mean, why not?

It's less than you spent on your cartridge, isn't it?

It really only fails on the sexy quotient.

Have fun!

@lanx0003 The KRELL Duo 175XD was used on my Thiel CS3.7 and also my RAAL SR1a earphone using the older amp interface box. Interestingly, the SR1a drew more power out of the amp. I knew this because when I used the CODA #8 in place of the KRELL I could see the meters on the amp flying for the SR1a but not move for the Thiel CS3.7. I had both KRELL and the CODA on hand.

When I used the KRELL as a earphone amp I had the amp about 1 foot from my seating position. I never heard the fans.

Here is something on both the KRELL and Westminster Labs amps that I posted about earlier. Class A amps that stay cool.

WestminsterLab, LampizatOr, VSA and Hear This | AXPONA 2024 - Part-Time Audiophile (

I now use the Schitt Aegir amp in place of the CODA and the KRELL using a new RAAL amp interface box. It is rather good, not as good as the CODA or KRELL, but I only need 20-watts Class A with the new RAAL amp interface box.

The Aegir is mechanically nosier than the KRELL with fans. The new Aegir 2 is supposed to remedy that mechanical noise.

The CODA #16 does get warm generating the first 100 watts in Class A, but it is not very hot.

...something that came in the 4/30 email that ought to give more bang v. bucks for the D lurkers....

... or those with a lust for power beyond nominal sense... ;)

...and seems to have certain 'play with' features that may attract....

FWIW, we make a 5-Watt/channel class A tube amplifier that can sit on a sheet of notebook paper with room left over. I designed it for my bedroom system.

@atmasphere, what speakers are you using with it?

Yet another vote for the Schiit Aegir. The Aegir 1 is class A up to about 10 watts/ch.  It does run warmer than a class D amp, but nowhere near as hot as a KT88 tube amp gets. 

The Aegir 2 has just been released and they list for $900. It has a bit more power than the Aegir 1 (which I have) so you can buy the 1 for a lot less than the new one. And, as others have noted, if it doesn't float your boat they have good resale value.