am i going to need a capacitor? if so,what size? im running a kenwood 7120 h/u, 2 sets of spr 13c in doors. and type r 10'' sub. sub is running off an alpine mrd-m6o5 mono amp. and speakers of a 600 watt 4 channel amp. thanks again guys

 

What class are the amps?

If they're the new Class D amps you should be fine without a cap.

 

you'd be fine without one but id go with a 1 farad cap to be safe

 

A cap won't do much besides condition the power to the amps... upgrading the big 3 would help out.