Audio Difficulties

[mexx]

For some reason I can't hear audio online - specifically Youtube, itunes music sampler, amazon music sampler and the like.

Streaming Windows media player works fine, as does Realplayer but I can only get partial sound channels on Quicktime videos (tbackgroundmusic works but I can't hear any speech).

I can't even hear the system midi/wav files in Windows XP when I try to test them yet I can play mp3s and videos fine on Media Player Classic.

I've tried uninstall/reinstall of flash player & all the different media software. When that didn't work I tried installing various codec packs like K-Lite and XP Codec. I cleaned up my registry and checked to make sure I have the appropriate files in my system32 folder but so far no luck.

Can't see any problems or conflicts in device manager. Not sure what to do next. Any help would be most welcome.

 

[mexx]

Yes, the speakers are plugged in correctly.
I use a Monster cable with headphone sized jack one one end that plugs in to the soundboard on the back of the PC and the other end is a pair of red/white stubby connectors that I have plugged into the audio IN on the back of my Sony ministereo which has 2 fronts and a center wired to it.

Under Control Panel > Sound & Audio devices I had to switch the speaker settings to Quadraphone or higher to actually hear anything. Maybe this setup is messing things up?

But like I sadi, the problem is not that there isn't any sound coming thru as I can hear most of the files in my music folders (if I use Mediaplayer Classic or Realplayer), just not most of the online audio.