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.



@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 )