Anyone have after market sound system cause battery/alternator issues?

[IMOLAredNC4.8is]

I have been doing a lot of research on the typical " transfailsafe, dsc 4x4 inactive, self level susp inactive, lose of power steering, abs light, tire pressure light, nav screen flickering on and off " issue. Took the car to the dealer and they tested the alternator and they say its fine.... The only thing that makes sense would be the alternator going bad. I started to thing about terminal connections and i thought back to my sound system. I had best buy install 2 10" subs about 1 year ago. They connected directly to the terminals. I am thinking this could have cause the issues. Mabye the sound system was drawing too much power from the battery and the alternator could not keep up to charge the car so therefore I was loosing power to all my accesories. About one week ago completely disconnect the system and the problems are still present. I took the car to the dealer they could not find any thing wrong with the car. The service tech drove it home two nights in a row and the only resolution they came up with was replaceing the EHC module. ( controls dsc and self level suspension). I am picking the car up this afternoon praying that this solved all of the issues. Could it be possible that the alternator or battery is bad even though it is testing good? And even though I disconnected the system could it have permanatly damaged the battery and alternator. If anyone has an knowledge about this issue please help. Always appreciate the help I get on her, Thanks alot guys.