Other posts have answered your questions pretty thoroughly. I would add just a few comments. The Marantz web site claims the SR5010 can handle low impedance loads, so if the CM1s dip much below 8ohms, that may not be a problem. At under 23 lbs and delivering over 70 watts x 5 into 8 ohms and capability to handle low impedances tells me this is likely a switching amp rather than more classic AB type. Switching amps are getting much better sounding, and I have heard the CM1s sound very good with 500W per channel Rotel switching amp. That is in part why I like more power for these very inefficient speakers. Ultimately it depends on the size of your listening space and the volumes you prefer, but I can envision circumstances for rock or classical music performances, or a large dynamic shift during a Blu-Ray where more amplifier headroom would be appreciated. Just saying...
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