Don't forget speaker efficency(SPL Db/w rating)..
We have been through this before...but just because someone has some "big speakers"(say 15" 4way's or such) and a "big amp" (200+ w/ch) does NOT necessairly mean that it will outdo a lower powered amp/speaker setup.
In fact(experts feel free to add to/correct this if I am wrong), but in MANY cases-- that 200 watt setup could be BEATEN by another setup with a 50 watt/ch amp. it ALL depends on how efficent the SPEAKERS are!!
A speakers sensitivity is measured in Db/w at 1Meter. (I THINK) this means that , with 1 watt of input, a given speaker will produce a certian level of sound power, when measured a 1 meter(3 foot) from the center of the speaker, measured with an SPL meter.
So, say one speaker has an 85 DB/w rating, but another one has a 95 Db/ w rating. It would take TEN TIMES the amount of power to get the SAME amount of sound from the 85Db speaker as it would from the 95 Db speaker!! IOW-- (all else being equal), a 25 watt amp could produce AS MUCH sound from the more efficent speaker as a 250 w. amp would from the less efficent one!!
So--it is not "just about watts". A good number of people around here have systems that only produce 10 watts or les of VERY pure power, fed to some 100 Db/w speakers or even MORE efficent..and those could BEAT a LOT of 200 watt systems!! (Myself, I have a 60w/ch mosfet ssytem, feeding 4 -94 Db/w. speakers, and it can REALLY pound, when I need it to!!)