Sounds like a normal issue to me on most every computer with a front bezel jack, as usually the front headphone jacks over power the backside jacks due to your sound card. Remember you don't have two sound cards working at the same time. & a front bezel jack is not an extra soundcard, it's just a cabled extension of your actual pci soundcard or onboard sound. It's like trying to write with a pencil that has to sharpened ends (you have to pick one end to write with). I would try one of two things.
The first trick would be to open up your pc case and unplug the wire that connects your front audio jacks to the soundcard or onboard sound. You wouldn't have to disable anything in windows because this is a hardware component add on which adds front bezel sound jacks to your pc case. It has nothing to do with the options in your windows mixer or soundcard mixer settings in your operating system. What you would than have to do is whenever you want to use headphones you'd have to unplug the speakers from the back jack and plug in your headphones. Unless your speakers have an audio input jack on themselves. Than you would just plug in the headphone to the speaker jack which would over power the speakers and bring sound to your headphones. This is only one of two solutions.
The second trick would be to go out there and purchase a cheap mixer. You can get one for under $100.00 or less. You'd be able to plug many things into the mixer of your choice. Of course that means headphones, speakers, monitor speakers, etc.
Oh and lastly something else just came into my head. This would probably be the easiest solution. Just go out and by a dual headphone jack splitter like the one below and plug it into the back of your pc. If you do so never use the front jack bezel on your case (you can keep the front bezel connected to the soundcard/onboard sound inside your case). But just don't use the front bezel jack or else you'd have two wires on a splitter there which would look ugly. So use it at the back! & Make sure it's a gold splitter not a metallic one. The gold ones offer better sound and give you more quality as they don't tend to rust like the metallic ones. You can buy these at Radio Shack or Circuit City for $5-$10.
Hope all goes well!
Edited by superstar, 27 March 2008 - 12:10 PM.