Lots of BS floating around here.

This amplifier is Class D which means at max output its efficiency can be 90%. To get 250 watts from 14.4 volts requires 17.4 amps. Dividing by 0.9 gives 19.3 amps. But let's consider voltage drop from battery to amp and guess it at 1.5 volts, now flat out the amp should draw 22 amps. That should be the max. Volume set on 10. For everyday driving the average power used should be more like 1 watt to get 90db, 2 watts to get 93db, 10 watts to get 100 db, 100 to get 110db. I think the calculations are right. Twice the power increases by 3 db, 10 x the power increases by 10.

So the maximum amp draw should always be less than 22 amps.

The minimum wire size suggested by kicker from battery to amp is 8 gauge. I'd agree bigger is better.

The amp will use your high level output, like a speaker level output, to get the signal. Or they will take line level (preamp level).

I'd say the system will work in your car as long as you aren't entering any sound level competitions. If you have added any extra power drawing things like electric fans you may need a 65amp alternator, otherwise you're probably all right. I'd run both positive and negative wires from the battery to the amp and put it closer to the front like the package shelf rather than in the back of the trunk. Make sure you use fuses.

I'd hold off on capacitors until I found a need. This forum is full of people who love to spend other people's money. They make only the best suggestions about ideal installations or equipment. On their own they might choose much less expensive gear.

R.