How much watts does my amp need to be if i want to run a 400 watt sub. and would my amp need to be mono or 2 channel, or doesn't it matter coz i'm not quite sure what the difference is! please help!!!
If you want to run just one sub you can get a mono amp, or if running a full system you can choose a 2 or 4 channel amp, if the sub is 400 rms then any amp with that power rating should suffice or a 4 channel or 2 channel that you can bridge
just for the record, you can run multiple subs from a mono amp. class D amps are most often mono, and made just for driving subs. You'll have a hard time finding any class AB multi-channel amp that can produce more than about 500 watts per channel RMS at it's minimum load.