I have the Paradigm Studio 40s v2 and I originally was using a Yamaha RX-V995 to power all speakers (I have the 40s as my mains and surrounds and the CC as the center). The Yamaha is rated at 100W per channel and did an admirable job as moderate levels. I'm now just using my Yamaha as a pre/pro and using a separate amp, the Anthem MCA50 (5x225w)to power the speakers. I found a substantial difference ... especially the dynamic range, head room, cleaner sound (a lot less distortion). I moved to a separate amp because I moved my HT to a bigger room and I like to listen at reference, and the Yamaha could not keep up (too much distortion was introduced, making it sound too load). With the new amp reference doesn't sound as loud ... don't get me wrong it is LOUD.
The amount of power you need ultimately depends on the size of room, and your listening levels. I am of the belief that more power is better than less, as distortion will ruin a speaker more so than power. I have reference as a goal, and I'm almost there. I can drive my speakers no problem, but my subs only

produce 115dB at 20hZ.
I'm very happy with the Anthem MCA50. I found this amp to be a very good value option especially here in Canada.
Good luck!
Mass