I'm sorry to say that most of the responses you've received are not useful, and some are nonsense. (There are some good ones too, so don't everybody feel insulted.)
I'll try to help... In general, more watts are not needed for more volume. They are needed for more 'headroom'. In a musical recording, the transients (leading edges of any sound) are MUCH higher amplitude than the rest of the signal. Having plenty of headroom allows your amp to produce those (fraction-of-a-second) transients at full volume without attenuation or 'clipping'. That results in a much richer, more robust and more REALISTIC presentation.
It's also true that less efficient speakers will perform better with plenty of wattage & current, because they simply need more power to 'sing'. I tend to like the sound of low-efficiency speakers mated to powerful amps, but there are many exceptions (& that's my personal taste).
That being said, your Revels are rated at about 88 dB sensitivity w/ nominal 6 Ohm impedance. That is a moderate, rather than difficult, load, and should not require 400 W/ch.
What's more important is the QUALITY of the amp! The Ayre V-5xe is a nice-sounding amp. You could easily find a mega-watt amp that is not so well-designed... and take a step BACK in sound. I would try to audition the Revels with a more powerful amp before spending any $$. You may find that there's no real advantage.
BTW... what pre-amp are you using? Have you tried a tubed pre-amp? I've had great success matching solid-state power amps with tubed pre-amps (incl. my current system). That gives you the tight, well-controlled bass associated with solid-state as well as the beautiful mids & highs that only tubes seem to provide.
Anyhow... I hope that helps.
