No Music From Headunit

If you read the post "electrical problems" you see what my prob was before. It ended up being the fuses. So anyhow, today we hooked up the Alpine CDA-9831 and it was working good. Then the vocals went out completely. If I put a cd in you can still hear all of the bass tones but no vocals or music. Also some of the interior dash lights are out again, possibly a blown fuse I'm assuming. Any ideas why the headunit would work for a while then go out. Some of my friends said it could be: something with the rca cables, the 4 channel interior amp is blown(still turns on I believe), the interior speaker(s) are blown, or because the new headunit has 4volt preouts while the previous headunit had 2volt preouts and we left all the settings (such as the gain) on the 4 channel as is, it blew something....Any ideas? Thanks in advance.