More watts or better power ?

There’s been lots written but here are my two adds: one more factual guidance, the other my opinion based on hearing various Sonus Fabers.

1. re: power vs quality - more power is only beneficial if you are exceeding the VOLTAGE limit of the amp. The Pass labs stuff can deliver plenty of current for its modest voltage (about 14 volts rms) under normal dynamic conditions (where one uses on average ~ 10-% of rated power due to music’s peak: average ratio) . If you are beginning to clip - get more power. Else. move on IMO. Note my answer assumes that money is limited and you can only spend your budget once: so money spent on an amp, for instance, is not spent on speakers.  Hint: i think you ought to look at speakers - whether i be subwoofers or a thoroughly different speaker. Yet that may not match your personal likes.

2. re: the speakers - it would be helpful to know the problem you are trying to solve. They will never have much bass - the laws of [physics are not on thier side, yet many speakers that solve that problem violate the laws of decorating. Only you know.

That said, when i have heard the Sonus Fabers they always sound somewhat bright and harsh from the upper mids up. This is, IMO, common in many components that seek "detail". It does not sound like music to me. Don;t get me wrong, they are very good speakers, but IMO nowhere near the quality of your preamp and amp (having only heard *ABOUT* the BHK, but knowing Nelson’s stuff).

Yet that may no be your objective at all. Step #1 if finding a solution is knowing the problem!

G

Audiophilia nervosa? We all have it.
Powered subwoofers and external crossovers to reduce the bass load on the Amators might be worth trying.
You have great stuff, by the way.
Have fun!

+1 for Silversmith Fidelium speaker cables. They are not expensive and probably the best available at any price. A no brainer.
Then as good a cartridge as you can afford. Source is critical.
If your amp is not clipping, you will not benefit from more power.
It is always tempting to get a bigger amp but not needed.
You seem to have a very nice system especially for a small room.
The Fidelium SC have a trial period but you will not send them back.
And the cartridge is where the sound is coming from.

I love the XA25. I own one.  If it already plays loud enough.....

So.  Cross the subs at 80 to 100 Hz.  Then you for sure have enough power.  The drivers in your speakers will vibrate less at lower volumes clearing up the sound, less IM distortion.  And the subs will increase dynamics.

Also, unless I missed it do you have your speakers isolated? I want to try this as well.  Supposed to clean up several things.  Soundstage for one.

If you want to try a different pre amp, a Don Sachs or Supratek are high quality for 2 to 3 k.

Your amp plays loud enough so keep it.  Subs crossed at 80 Hz or so will take more load off the Xa25.  The speakers will sound better with less IM distortion.

Don Sachs and Supratech make excellent tube preamps if you want to try one.

Speaker isolatIon is another thing to consider if not done.