Help with diagnosing sound problems on Dell 8400

Hi everyone,

I have just joined as I wanted to get some advice on diagnosing my sound problems with the 8400. I have it since 2004 or '05, not sure exactly, and it has been my fairly reliable workhorse PC that I tend to leave on all the time. Yesterday I was playing some music and the sound went funny on it. I didn't lose it altogether but there was a crack and everything sounded like it was underwater. Lower and kind of muffled. The four diagnostic leds on the back were all green.

So I tried taking out the SB soundcard and switching to onboard sound, my logic being that if something had gone wrong with the motherboard/ buses etc. that the sound wouldn't work on that either. So I plugged the speakers into the other output in back and the sound only seems to be coming from the subwoofer boxy part of the dell speakers. When I popped a pair of headphones into the output it seems to be fine. The sound isn't as crisp as I am used to with the SB sound card but I'm guessing that is why Dell offered the SB card in the first place. Would I be correct in thinking it is just the speakers themselves that that have gone on the fritz?

I have another setup with an amp and speakers connected to another PC I use as home theatre but I had to get the help of a friend who's no longer around to get that all set up and I'm loath to go messing around with it and try swapping stuff back and forth, mainly because I might not be able to get things back on the other setup and not knowing about it I 'd be afraid of blowing a circuit or something.

I hope this isn't too garbled an explanation. Naturally I don't want to replace the speakers to then find out it was something else altogether.

Any help in troubleshooting would be appreciated