Hello, I have a early-2011 model 13" mbp. The audio output sounds very tinny and compressed distorted. This has been the case for a while now; initially I thought it was my headphones, but recently I had to play through some external speakers and it sounded horrible. I am almost certain it is a hardware issue. It sounds bad both from the built in speakers and the audio output jack. I have booted from both ubuntu and lion on an external HD and the problem persists. I am still under applecare warranty, does it cover an issue like this?