lookin for an amp for fronts rated at 100w rms and rear rated at 90w rms.....looking at kicker zx350.4 for 90x4 rms(2o) or zx650.4 for 120x4 rms(4o)......would it be better to get the 650 and run it at like 3/4 for longer life? the 350 would be like 50 cheaper though. any thoughts?