More power "better"

i don't own proac and i do use tube amps. i have a pair of very effiecent speakers (jm labs mezzo utopias) that can run on anything from 50-200 watts. when i first bought them, i ran them through a 45-50 watt tube amp (cj's mv55). they sounded great. shortly thereafter, i replaced the amp with cj's permier 12 monoblocks wich produce about 140 watts per channel. the difference was, as many audiogon audiophiles would expect, incredible. better bottom end (the increased power helped the woofers move in and out more completely and accurately) and sharper detail through out. some of the improvements can probably be chalked up to the amp itself, however, i wholeheartedly beleive that the added power enabled my speakers to perform better. in terms of how much power, what is the manufacturer's suggested range, what type of music do you listen to and at what volumes? i think a safe (and hopefully affordable) bet would be to try and buy an amp (or amps) that deliver enough power to put you right in the middle or 60-65% range of proac's suggested range. although i own cj, i very much like some of vtl and ar's offerings. in my experience, today's tube amps are pretty reliable. they may or may not be for you, but don't cross them off your list without listening--don't worry about their reliability. like anything else, if you buy quality you should be okay. all of that said, be mindful of the fact that searching out and purchasing nos tubes is a fun, but expensive, habbit. good luck.