sudden problems w/audio playback quality (distant vocals, e.g.)

[elonkra]

First noticed the problem while listening to mp3s in iTunes. Opened the same files in Windows Media Player and Media Monkey, and the problems are present there as well. Tried iTunes help, google, Windows XP help, not getting anywhere. No reason to believe I need to update a driver. No reason to believe anything is jacked up on my volume control settings. No clue what to do. Any suggestions would be greatly appreciated. Will provide any information needed, but I'm not really sure what's needed. I've been through several troubleshooting/diagnostic tests. Disabled Sound Enhancer & Sound Check in iTunes, searched this forum for all posts w/iTunes in the subject line over the past year, nothing on point.

[elonkra]

driver tool guide results

Here is what I found from a program I downloaded called driver toolguide. I've been told that I might need to make sure I have up-to-date drivers and/or sound cards, but I'm pretty computer-illiterate in this context. I don't know which of any of the items listed in the image above are the drivers or sound cards in question that I may or may not need to examine and/or update, but I would appreciate any input or insight that y'all might have to offer in this regard.