I've done this a couple different ways. I've used my five-channel amp (a Model 750, 165Wx5) for the mains, center, and side surrounds and then used (briefly) an old stereo receiver or (for a couple years) a used Parasound HCA-800 Mk.II stereo amp (bought off Audiogon for $150 or so). I've also used my five-channel amp for the center and four surrounds along with a pair of M200's for the mains, which I switched to late last year after the old Parasound got flaky.