Considering A 20-40 Watt Stereo SET Amp

as @three_easy_payments has identified, your speakers are the determining factor here. You are really going to have to audition a range of tube amps before purchase as the results of the complex speaker- amp output stage interaction can not be predicted accurately from specifications and will tend to dominate sonic outcomes.

Conventional wisdom would dictate that those amps with a 4 ohm tap would be more successful. However, this may not be the case and each amp should be auditioned on its own merits.

I would therefore caution strongly against falling into the trap of auditioning a single recommended amp and buying it because it sounds nice (most tube amps sound nice), and instead make a point of auditioning a range of different tube amps before you take the plunge on your favourite.

I would also have a really good SS power amp on hand as a baseline reality check as to the overall viability of tubes with your speakers.

@stereo5 Wrote:

 

Considering A 20-40 Watt Stereo SET Amp

Maybe 8 watts!

Look at the Coincident Dynamo 34SE MKIII integrated amplifier. Price: $1799 US

See below:

Mike

https://www.coincidentspeaker.com/mpsip_amps.html

I have decided that it will be too costly to buy a SET integrated with all the features I need so I have decided not to go any further.  I am not willing to compromise on a push pull tube integrated (been there, done that) so I surrender.  Perhaps in the future if I decide on a pair of Klipsch Cornwall IV, I will rethink this again. 
 

I want to thank everyone who contributed to this thread and a special shout out to Aric Audio, thanks ever so much. 

@stereo5 What you are up against is that its really hard and really expensive to make power with SETs. By really hard, one of the aspects of that is bandwidth goes down the more power you need (due to output transformer limitations). That is why the smallest SETs have the reputation for sounding 'the best'. By the time you get over about 7-8 Watts (300b territory) you have trouble getting the amp to have what might be considered 'hifi' frequency response.

When people compare SETs to PP amps, its usually an apples and oranges thing! That is because the SET has no-where near the power of the PP amp, and the PP amp doesn't have Directly Heated Triodes, like nearly all SETs do, and likely runs feedback and pentodes as well.

To put that PP amp on a level playing field with an SET, they should have the same or similar output power at clipping. People don't do that- because there are almost no PP amps that only make 5 to 7 Watts! And no-one even considers putting a 30 Watt SET against a 30 Watt PP amp. It would get creamed. That's mostly because at that power level, the bandwidth limitation imposed by the output transformer is readily audible. And measurable as well... and the PP amp would have a much greater amount of usable power...

RE usable power: SETs rarely use feedback so their usable power is up to about 20% of their rated power. Above that power level, they take on a 'dynamic' quality as higher ordered harmonics show up on musical transients (where the power is needed). The ear uses the higher ordered harmonics to sense how loud a sound is, so when they are only on the transients, you get a 'dynamic' quality.

Dynamics should come from the signal, not the amp.

If you are not willing to replace your speakers, which are not efficient enough to really work right with most SETs, then look at a PP amplifier. There are triode PP amps that run class A with zero feedback, FWIW. IMO/IME they sound better than SETs too: more transparent (due to lower distortion), more authority (due to better bass power response) and overall more true to the signal- the music.

SET guys won't like this of course, but I challenge any one of them to a simple set of questions: When did you compare to a PP amp of the same power? Barring that, did you compare to a PP amp using the same power tubes and construction technique (and parts)? I've done both. I can go into in depth...

@atmasphere 

SET guys won't like this of course, but I challenge any one of them to a simple set of questions: When did you compare to a PP amp of the same power? Barring that, did you compare to a PP amp using the same power tubes and construction technique (and parts)? I've done both

I suppose am a “SET guy”.  I’m not the least bit bothered by this and I haven’t done the above stated challenge. In my audio journey, if I’ve learned anything it’s choose what type of sound and music presentation that makes you most happy and connected.

I have owned two terrific push pull tube amplifiers, 100 watt KT 88/6550 and 40 watt el34. I have 300b SET mono blocks 8 watts. All three work very well with my 94 db sensitivity/14 ohms speakers. The SET is the most nuanced, open, transparent and in addition the most emotionally involving, 3-dimensional and tactile of the three amplifiers. Simply more real and believable presentation. That’s my listening experience. For other listeners if can certainly be different.

@stereo5 I strongly encourage you when the time is right to obtain suitable speakers and try a good quality SET. See what you think. Maybe even do the amplifier challenge mentioned above.  It may or may not be for you.  I can only report that it works extraordinary well for my desires.

Charles