Headroom is always nice. I believe it also helps with the dynamics of music as Alton said. Just an example in my case: Say I set the gains accordingly and I'm getting about full output from an amplifier rated for 100watts. Now I lack a little midbass, and want to add a little EQ to an area, say I adjust some midbass region up by +3dB, that's now going to require twice the amount of power, but the amps pretty much already at it's limits, so that region that I tried to make louder may become "clipped" and distorted. I believe that's also why people like to EQ stuff down, instead of up. Now if the amplifier was rated for 200watts, but I had it set near half power, then it would still have 100watts left for that region I EQd up. That's a rudimentary example of what can happen when EQing, but it's also similar to music being dynamic (it will have various frequencies, and all at different amplitudes.) So the "extra" power can provide better sound before the amp reaches it's limits and causes distortion. At least that's my crude understanding. ------------ Depending on your goals, yes you can run sets of speakers on channels, but that also depends on their resistance, and how they are wired. I wouldn't judge a speaker by it's RMS value, although it's often misused as a marker for "quality" or "getting louder."