Aug 06, 2006 07:37 am Welcome to HRC.
From what you posted, my first guess would be that the adapter / cables are not working correctly. I've seen many times where when an adapter jack starts failing, one side is weak.
Try another cable if possible, or at least re-seat all jacks and cables.
Now, to theorize wildly:
Try different speakers. Or, try your speakers playing on some different system (ipod, tape player, etc). This will ensure the speakers are working correctly.
If your speakers are known to be working correctly, and your cables are known to be working correctly, then it has to be something in the computer.
If you're using windows, then in the volume control applet, maybe something is panned off to one side. Ensure that's not a problem.
If that's not a problem, then your software (emu's control panel, or the program you are playing 'music and stuff' with) may be panned to one side. Make sure all that is correct.
You may want to switch your program, or emu's control panel, to play in mono. Just to see if that balances out the signals. If it does, then the problem is in your software somewhere.
Good luck.