Looking at wiring in a underseat subwoofer and rear reverse camera where's a good place for a 12v source preferably off when ignition is off to drop battery drain.

Cheers

Whats the subs current draw? You'd be best looking at a relay off something that ign live (eg stereo or cig lighter) and then going to the battery or the main cabin power supply distribution near the fuse box for the main power. You need to know what the peak current draw of the sub is though.

I've heard the rear wiper is a switched live. Not 100% though. Have to get a multi-meter out and start checking wires!

 

Regarding the sub aren't you best running it directly from the battery as said above? I'd imagine there won't be any internal wires with the capacity to provide enough juice needed for an active sub!

It's not always on, there is a pilot 12v feed that comes from the head unit that tells the sub to switch on/off when the head unit is powered up. So while you could argue the sub is always in standby mode I don't imagine it would draw much if any power in it's idle state, certainly not enough to be worried about. The only way to truly isolate it and cut the main power when the key is removed is to use a relay on the 12v feed from the battery somewhere but why add complication and another component in which could fail.