I'm afraid I may have irreversibly harmed my internal speakers, or sound system in general.
Yesterday, I was trying to find a way to hook up my electric guitar to the computer. I, logically, thought that going through my amp and running the amp to the macbook line-in was the best course of action.
What came through my external speakers was just muffle-ly cracked noise that were very unstable sounding. After failing to get a decent sound, I found that my sound in general sounded really weird.
Now I get sound through the headphone jack, but it has odd sound artifacts around any sounds that are played, and when removed the internal speakers do not make any sound at all (but APPEAR available on the system and I can still adjust the volume). Here's what I've tried so far:
Tickling the sensor in the phone jack, managed to turn the red light on and off several times. No effect.
Hardware reset (by holding the power button for a while... could not hear the system "dings" though, due to the absence of sound)
Logging in to Linux partition. Same problem there.
Changing sound inputs a couple times and starting up and shutting down garageband with new and old projects.
Any other ideas? Or have I permanently harmed my sound system?
EDIT: Wanted to add that this macbook is past warranty and there's no apple stores nearby anyway. So I won't be taking it to a retailer.