I have owned two examples of the XA25 and tried them with 5 different speakers. In a medium/large room, I concluded the Pass really need be paired with speakers of a true 90dB sensitivity at minimum. The XA25 is one of those amps that sounds great at most listening levels but for those times you want to push it, there isn’t much headroom. The compression kicks in quite suddenly.
An amp I recently acquired that sounds very similar but with much better headroom is the Ayre V-5XE. You might come across reports that this amp is “light in the bass,” but that hasn’t been my experience. I suspect those anecdotes might have arose from a speaker being wired out of phase, which is an easy mistake to make with the mirrored configuration of their binding posts. It is not a bass monster like some Parasound amps, but it’s certainly no lighter in the bass than the XA25.
All that said, I disagree that the Pass sound is so “unique” that it must be auditioned first, especially with the XA25. If operated well within its limits, with efficient speakers, the XA25 produces end-game sound quality and engagement.
