Yes, way more than 5 amps. A typical amp for a sub will have a cable feeding it the same size as the one going to your starter. The capacitor acts as a power storage so every time the subwoofer booms, that amp surge comes out of the capacitor instead of straight out of the alternator. Run a decent size amp with no capacitor and your headlights will dim with each boom of the sub and you will fry your alternator. I don't bother with this stuff anymore, but years ago I learned some of these lessons the hard way.