head unit cutting out

Check your grounds and power connection.

 If you are using the powered output from the built in amplifier make sure that the speaker impedance in not lower than what the alpine can take- usually 4 ohms.

Try disconnecting all speaker from the alpine and run with high volumes and see if it cuts out .

sounds like you have a grounded speaker.  one way to check is to fade and balance to each speaker turning the volume up on each one.. the one that makes the radio cut off is the problem speaker or wire..

Of course, you didn't say whether or not it was the unit actually shutting down, I'm assuming the audio would quit playing while the deck stays on (It's still lit up) If the unit is shutting down, as he said, check the voltage.

Hi, I just installed an small amp (175 Watts RMS) in my car to power a sub, and while I was testing it, at high volumes when there was a bass hit, my speakers would distort, due to the head unit cutting out. This didn't happen before I installed the amp at the same volume levels. Is my alternator not able to supply enough juice?

Also, after running the system for a while I noticed that 4 wires leading to a relay for the ECU were melted. Could this have anything to do with the amp?

Any help is appreciated.