My PC's mobo has a Realtek ALC883 sound card with a header for a front audio panel. I bought a front panel unit that has headphone and microphone jacks along with USB and Firewire jacks. There were 2 plugs from the audio panel, one Azalia and one AC 97. The mobo manual is pretty clear on the ALC883 being Azalia so that's the one I used.

Everything works but the sound through headphones sounds like AM radio. The same headphones sound great with an iPod so I don't think that's the problem. I've installed the latest sound driver and adjusted all the relevant settings I can find.

Any suggestions?

Surely in this collection of fine minds someone has an idea?

Cabling, EMI (electromagnetic interference), drivers, bad card bad connector, faulty solder, take your pick.

Did you check the Realtek config app and/or wizard. (i think it's called HDRealtek Audio or something).
It seems the driver doesn't assume by default that the jacks are what common sense dictates they should be. I had to run the wizard and tell the stupid thing that it was speakers that I had plugged into the green speaker jacks before it would work.

Also, there was momentary confusion on my part as to whether "Front Speakers" referred to front speaker jack or front speakers in a surround system.

That said, your symptoms do sound like bad jack, cable, or something as mentioned above, but check the config if you haven't because the default settings will probably be wrong.

Yes, I've checked the settings and so on.

Here's another question - Realtek's website says they're a chip supplier, not a card manufacturer.

My mobo (ECS P965T-A) has onboard sound but I'm not clear on the configuration in such instances, is there a card or not? Would it make sense (and solve this problem) to just install a brand-name soundcard?

My opinion (not that it's worth much) is to just spend a few bucks on a seperate soundcard. I hate to spend extra money when I don't have to, but you can get a 5.1 digital card for less than $20. Or a standard card for $5. Make sure you go into your bios and disable the other card before installing the new one. Oh, and make sure the one you pick out has a plug for your front headphone jack. My time is worth more than the few bucks for a seperate card that is probably better than the built in card anyways.