It's not incompatibility with AMD specifically, it's that VIA and SiS are both completely incompetant. The amount of resources that must be spent supporting VIA chipsets and the like has historically been so great that a lot of manufacturers offer incompatibility warnings so that they can ignore you with less guilt.
The truth of the matter is that m-audio products can work just fine in an AMD system, and you can have problems getting ANY system to work. Statistically in this realm it appears as though you will have a better chance at success with an Intel chipset, but the odds are not drastically stacked against AMD. From the complaints I've seen here and elsewhere of clicking/popping and dropouts and the like, I would say that about 60-70% are from people with VIA chipsets...and really, that's not such a majority that a person can conclusively say that Intel chipsets are better than VIA chipsets when it comes to recording, especially when we haven't determined specifically which chipsets we're comparing. Not to mention that most people who can't get a system to work have very little experience. Is the Intel BX chipset better than the VIA MVP chipset? By fucking miles it is so much better, and is why VIA got such a bad rap and for a while people were advised to ONLY buy Intel (also the K6-2 processor sucked eggs)! Is the i845 chipset better than the KT133A chipset? I think so, but plenty of happy AMD owners would disagree! So there you have it; take your chances.
Slackmaster 2000
P.S. There are no good SiS chipsets.