Problem with Audio in/output

This problem started after the Lion upgrade. The Imac worked almost perfectly before this upgrade. Apart from this, I also had problems with the Imac screen itself, but I managed to fix that... Of course this all started after my warrenty expired... So typical for Apple.

I can't use the Headphone/Audio Line-Out Port. When I put my Apple Earbuds in my Imac 21", Late 2012 all I hear is a loud noise. The earbuds also get very hot. They do work on my Ipod so they're not broken. When I put an aux-cable in the audio port to connect it to my speakers, I hear the same constant noise but much louder. I have to use an usb interface to connect my soundsystem, but I can't fully use it because I would still need the audio port.

I need to get this fixed, It's sad how I can't even use the audio port on a 2000 Euro machine, and I'm not the only one with this problem.