760 SFF Audio

I have a 760 SFF which was loaded with a memory stick from Dell with the Media Recovery disk on it. All was well for almost 14 months. A few weeks ago I had to reload the system using the Stick. The OS is Win7. Since reloading 70% of my on-line audio is clear and 30% is muddy.

I use the same Creative SB FXi via a USB  port. The same Media Recovery stick from Dell was used. 30% of my audio is so muddy that I can not understand it. Where do I begin?

tom_keltic