I have a 2003 M3 with the Harmon-Kardon sound system and Nav. When I push the left knob to turn on the radio, and it won’t turn on – no indicator light and no sound. The fuses are fine (shared with the Nav system, which is working fine). CD’s can be inserted and ejected, but won’t play. Any...

Ok so I am a complete noob when it comes to compatibility on amp, subs, etc. I have HK without nav. and I wanted to keep the stock HU. I don't want anything too crazy but I want a good "bump in the trunk". I plan on wiring a Kicker 2 channel (link below) tapped before the stock amp. Then, a...