The Cap stays charged so I cant see that much draw on the alternator, since its a battery, it can hold its own charge. High end audio users most likely (or should) have a seperate battery altogether, so theres no need to worry about messin around with standard operations power. Even with a larger battery I have a hard time seeing large output amps and subs hooked onto a battery without anything in between. A Bass Cap also improves sound quality, not a whole lot but a bit.