The now defunct Viahardware.com (I think it was viahardware.com) did a pretty comprehensive test of the SB Live problem. They duplicated the sound problem (crackling and/or looping) on Via chipsets (KT133A & KT266), Intel chipsets (i815 I believe) and a third chipset (possibly AMD 761). That is, they produced the problem on 3 or 4 motherboards. The concluded it was the SB Live.
There never was a fix but the workaround for the "crackling" problem was to limit Windows volume to no more than 50% and use your speakers' volume control to makeup the difference. This kept the noise floor to a minimum and made the "crackling" inaudible (to most ears).
I think the article is still hosted somewhere at Sudhian.com but I'm not sure.
The infamous VIA 686B bug was the data corruption issue. Supposedly any mobo with the 686B Southbridge was subject to the problem. It wasn't limited to SB live owners but SB live may have made the problem more noticible.
The data corruption issue is easy to test. Copy a 100 MB file from one location to another (HD to HD will work as will CDROM to HD). If the new file isn't identical to the original then your mobo definitely has the corruption issue. If it does then your need a fix for PCI latency.
George Briese wrote one fix, one that actually worked. It supposedly reduced PCI performance but it wasn't major.
There were other fixes that were supposedly included in Via 4-in-1 updates, motherboard BIOS updates, and Windows Service Packs. However, I've heard claims that these other fixes work and claims that they don't work.
I would stick with George Briese's Latency fix for VIA chipsets. (I have no idea if the fix works with AMD 760 northbridge + VIA 786B southbridge, though).
I would not even try it unless you actually confirm the data corruption issue. Data corruption is serious but treat the fix as a last resort.
I don't have any experience with KT600 but I won't touch one. I'm tired of VIA 4-in-1 drivers on my old VIA boards. The drivers constantly "break". The complaints of VIA mobos don't seem to stop to this day. With nVidia nForce2 around (but not perfect) I don't see any reason to choose anything else (unless you need IDE RAID).
That's just my opinion, of course.
<b>56K, slow and steady does not win the race on internet!</b>