GA-P55M-UD2 - rear audio Line Out not working (Realtek HD audio)

[trale]

My rig:

Case = Cooler Master 341
Core i7-860
GA-P55M-UD2 mobo, with standard onboard audio jacks (Realtek)
Windows 7, 64 bit

For easy reference, here's my mobo
http://www.newegg.com/Product/Prod [...] 6813128405

For some reason, my rear line-out is not working. I have a VERY basic audio setup - I'm trying to simply hook up a simple portable speaker to my system. It's as simple and foolproof as it gets - this speaker uses standard stereo audio jack that plugs into anything. It's worked with my MP3 players, other PCs, laptops, etc.

Oddly, the front panel speaker connection of my new system does work - it's when I try to use the rear Line Out jack that I don't get any sound. I've tried plugging into all the other rear audio jacks to make sure - no good.

I've also played around with the Realtek HD Audio Manager - tried every setting I could think of:
- making sure "Speakers" is set as my default playback device
- make front and rear output devices playback two different audio streams simultaneously
- etc

Any ideas?

[oggmonster]

Are you using latest drivers? Plug the speakers into the rear green output, then in the realtek control panel if you click on the green output. You should get a load of boxes you should be able to tick. Try playing around with those. You may even have to select it as rear output or something.