If you run dxdiag does it show any errors, this is really weird, have you disabled the onboard sound within the BIOS settings, but as you have said, same sound corruption with both sound outputs, so it looks like its going back to either windows or a codec thats installed.
Have you got any codec packs installed that may be causing the issue.
The only other thing is a complete reinstall of the OS, which would be a last resort.
i have reinstalled all the OS (XP SP3) just reinstalled minimal codec like said in the FAQ.. Sound is better but sound just like an overdrive...
Like a vibrating in voice....
Cons: This board is only good for things non-graphic intensive. The mobo has a regulator that throtles down voltage when the temp reaches 50 degrees, and this makes the whatever your doing very laggy/ choppy./// YOU CAN NOT TURN THIS FEATURE OFF!
Other Thoughts: Do not buy if you intend to play games at all. I don't even mean game slike Oblivion or BF2. This mobo will not even let you play flash games without throtling down the voltage. I used arctic silver and have three great fans.
i used mediaportal since a year on this HTPC and (a long time ago) all were ok.. no scratchy sound..
Perhaps when i changed my ati X800XL for the fanless 7200 GS... Not sure of that..
But the reinstall made the sound cleaner not pure but cleaner...
I have this issue too... in fact, since I had to reinstall MP from scratch from a recent drive crash. The recorded sound seems to be getting oversaturated as it passes thru the various stages of the bass engine (I'm only guessing). It sounds OK from MediaMonkey (which I had used to rip the CDs). I did notice it before on an earlier install... several months ago. Then, I mearly fiddled with all of the volume controls I could find in MP config until it sounded right. I did get it clean. I have to go over the controls again to find out the right settings, but I can't right now... I'm re-ripping my DVDs at the moment.
for what it's worth, I'd like to see seperate volume input controls from each of the MP media sections (TV,Videos,Music) so that I could equalize the volume output between them, so I don't have to make volume adjustments when I switch from TV to Music, or vice-verse.