Audio Output Issue

Hey all,

I have a 15" macbook pro 2010 with snow leopard and when i plug headphones in, or speakers into the headphone jack, the left earbud /speaker is crackly, muffled and broken up. Playing out of the inbuilt macbook speakers there is no issue.

The machine is not under apple care, so i'm trying to find a fix, if there is one.

Could it be the audio card, headphone jack, logic board?

Any ideas and fix it steps, would really be appreciated.

thanks in advance

-d