low power tube amp

Hi timber77,
Yes,  the distinction between SET  and SEP  was explained earlier in this thread. The actual tube in this amplifier is an 829b. 
Charles 

Klee123,
If the Focal  speakers don't work out you should really consider looking at more efficient and easy to drive speakers.  I think that this 829 SEP  amplifier you have is special.  The right speaker match would allow the amplifier to shine to its full capability. 
Charles 

Klee123,
I’m unfamiliar with this double tetrode tube. I’m aware of the company Finale Audio and they have an established and good reputation. This particular amplifier seems to be an all out effort toward high quality. I get the feeling that this is a very good amplifier design. I suspected it’d have "some" NFB as tetrode/pentodes aren’t quite as linear as pure triode tubes. I hope you can hear  the pairing, it could be really good! I like their attention placed on high quality transformers and chokes, always a good sign.😊
Charles

Klee123, This is why I asked earlier in this thread if your amplifier utilizes NFB as this will lower the amplifier output impedance and likely making it less susceptible to widely varying speaker impedance loads. Problem is that NFB can have adverse effects as well (depending on the amount and how it’s used). Ralph (Atmasphere) has covered this in excellent detail numerous times on this forum.

For example my SET amplifier has no NFB and has an output impedance of 1.2-1.4 range. This is pretty low for a no NFB amplifier but would be considered very high for the typical solid state amplifier. This works out fine for me as my speakers are 14 ohm nominal and have a relatively flat impedance curve.

So as Al has clearly explained the amplifier and speaker must have reasonably compatible impedance characteristics. You need more information about your amplifier.
Charles

Klee123, 
AL has provided you with with excellent technical information and explanation. 
Several questions.
What speakers are you presently using with your 20 watt amplifier?
Does this amplifier utilize NFB?
Have you any knowledge of the power supply design?
Most relevant,  can you hear the amp and speakers paired prior to purchase?
Charles 

Hi Al,
Agree with your assessment. Given that this is a KT 88 amp there may be some judicious use of NFB (lowering the output impedance) which "may" be beneficial along with a 4 ohm tap. An audition if possible will settle his case. If unable to audition then the safer choice would be a higher power push pull tube amplifier or solid state.
Charles

Hi Cymbop.
Quality can be had for reasonable cost as your amplifier demonstrates. It couldn’t handle your speakers if it lacked good solid design and parts. High quality parts don’t always have to imply expensive. For me the true test of quality is actual performance as opposed to price tag. 
Charles

Klee123,
A minor correction the KT 88 is a tetrode/pentode not a DHT (directly heated triode) so it would be a (SEP) single ended pentode )rather than a SET (single ended triode. Regardless,  if it is of good design, built and implementation it will sound very good. Good luck to you.
Charles

Cymbop,
Your 38 watt amplifier is able to do what it does no doubt based on high quality power supply design and transformers. Another (lesser quality) 38 watt amplifier could fail miserably with these same speakers. As you said, hook them up and just listen.
Charles

Hi klee123,
The potential problem would be driving the lower power amplifier into the range of clipping which could damage the tweeter. So it depends on how loud you listen and how hard you’re pushing amplifier.

Jperry raises pertinent questions, as there’s such variation among audio components. Two amplifiers rated at the same 20 watts can in reality be virtually night and day different as to their performance. The quality of their design, implementation, transformers and power supply could place them at polar ends of a spectrum. This is not exaggeration to simply make a point. Other than the same power rating (watts)there may be no other common ground.

If possible I’d listen to the pairing and judge based on what you hear. Depending on your listening volume and music genre you may be using just a few watts the vast majority of the time. Power is an important consideration but so is the overall  quality of the amplifier.
Charles