i have a sony high out put head unit in a civic which i don't really think too highly of civic's and lot of performance in any corner, although i do like their engineering. but anyways when ever i hit a beat even with the bass not even turned on and with the system off, the lights on the head unit dim. i mean if other lights on the car dim they don't dim enough for someone to tell. but couple times when i hit a beat it would draw enough power to shut the head unit off. i mean its not even loud to my ears. not to mention the volume is only turned up to about 6 to 7 bars, not even half way may be about (1/3).

what could the problem be? any ideas or advice?

 

The same thing happened in my accord, it means your alternator is going out and not providing enough power,you can have it tested at a auto parts store
or do a test by starting your car and taking off the positve battery cable and see if it starts running poorly and kills. i would recommend a high output alternator if you have a power hungry system or alot of accesories, or you can get a power capicitor which will help supply more power when the bass hits buut i would definetly get new alternator first (oem at least) because it will just get worse. My accord started like that then the tach and speedo would just die and then the car would kill the battery and die.