Adding a battery

[sjv13 10+ year member]

If you are using a line out you are definitely running the amp to hard. Look at the gain setting post in the amplifier section. Do it and if its not loud enough find the weak link and fix it

I know how I am supposed to set the gains with a DMM. I've tried it multiple times with a file from a flash drive and from my iPod through USB. Every time I get a reading that is way too low. Even if the gain is at max. I dont have an o-scope or know where to get one or how to use one.

EDIT: here is the thread I started a while ago:

http://www.caraudio.com/forums/wiring-electrical-installation-help/560754-troubleshooting-dmm-not-reading-voltage.html