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.

 

gregjacob

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.

Jerry

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?