Pass labs xa25 amp and BW 804 d3?

I'm using a First Watt F5 clone biased to 31 watts with a pair of Focal 936's (90dB sensitive). It in no way lacks the power to drive those speakers to any volume I please. The F5 and XA25 are similar, but there are important differences. The F5 is a 2 stage amp and the XA25 is a 3 stage amp. The XA25 has a meatier, higher voltage power supply, kinda like my build. It uses the exact same input JFETs as the F5. It uses current feedback instead of voltage feedback, like the F5. The real difference is in the massive output MOSFETs which don't use any kind of degenerative feedback, unlike the F5. That's an amp that will legitimately double it's power into half the impedance. The other notable difference is in the cascoded MOSFET gain stage that drives those massive output devices. If they're the ones I'm thinking of, they're kinda tough to drive with K170/J74 JFETs so the intermediate stage is required. The F5 is a very nice amp with a muscular, detailed, holographic sound. The XA25 is like the F5 built with a "cost is no obstacle" mentality. It does everything the F5 does, but better in every way. 

I know pass equipment and their Class A amps are quite powerful.
It should drive the B and Ws easily and sound very smooth and detailed.
If your room is really large and you need additional volume go to one of their Class A/B amps to get the extra power.  

As I said, I know Pass overbuilds his amps, and you might not have any issues, but once again, why tempt fate?
If it were me, I'd take the safe route and get a higher powered amp. I believe in having lots of headroom when it comes to power.
 Then if you decide to change speakers,you'll have a wider range to choose from.
I see some XA-30's for sale that are under $5K, still low, but closer to recommended specs. There are a pair of XA-100's, asking $6.5K though, but would be a real killer.
There are other manufacturers, but I don't know if Pass is the only one you'll consider.
Bob

Gweedoargus,
You have gotten some good responses and comments. I’m inclined to agree with those who have raised the very important consideration of ’sound quality ’ as compared to increased quantity (higher oower/more watts). The Pass Labs XA 25 is capable of 50 watts of pure class A into a 4 ohm load (this isn’t an insignificant amount). It can provide class AB 200 watts maximum into a 2 ohm load (This is impressive).

The John Curl designed Parasound A21 offers class AB 250 watts into 8 ohms and 400 watts into 4 ohms. So clearly higher power. I suspect it has pretty decent sound quality. Keep in my its DF (Damping factor) is >1100!! This suggests very heavy use of NFB. Some very respected amplifier builders such as Atmaspere and Roger Modjeski consider this amount of DF gratuitous and without meaningful benefit. On the other hand some builders (John Curl I’m sure) would beg to differ. My gut feeling is that the Pass XA 25 could very well be the superior sounding amplifier.

Is there the interest/desire to home audition these amplifiers and actually hear them driving your B&W speakers? I would bet that the vast majority of your listening the XAX25 would remain in class A operation. This is a good thing IMHO. I'm expressing my own biases. I don't believe in the cliche of "the more power the better" once you have sufficient power the objective should be placed on quality. 
Good luck,
Charles

I consider that kind of damping factor pretty ludicrous too. 500 is pretty typical for Pass's mainstream amps, and the XA25 certainly accomplishes that in no small part to lacking any kind of degeneration on the output transistors. 

If the XA25 isn't going to make the power you need, the XA 30.8 isn't either. But that's not why you should choose between them. They're totally different amps. The XA25 is a conventional push-pull topology with negative current feedback. The XA 30.8 is a balanced topology using Super Symmetry feedback. They work and sound totally different. 

I just crunched the numbers for those speakers. 25 watts will yield 101.2dB at 8 feet. That is insanely loud. Nobody listens at that kind of average volume. And 25 watts is just half of it's class A envelope. I crunched the numbers on the amp, too. It seems to be running 24V rails and hits 1% distortion into 8 ohm at about 22.8V. It's current limited to 10 amp, but you'll never see that with those speakers. At their 3 ohm low point that amp will drive 173 watts into them with current to spare. That's like 104dB at 8 feet. If you typically listen at an average volume of 92dB, which is still pretty loud, you only need THREE watts with those speakers at 8 feet.