Figured I'd at an additional data point.
I was using a dedicated laptop with Windows 7 and had all sorts of fun issues with audio drift with my ATI Wonder 600 USB. After fighting with it on and off for a month, I finally gave up after about 4 hours of additional testing today.
So, I went nuclear and installed Windows 10 1607 (has to be pre-Creators Update), blocked all methods for Windows Update, and installed the ATI Wonder 600 USB driver (was fairly easy to obtain, but I attached them here for posterity). Captured several hours of perfect video across multiple tapes with no audio drift. Soon to update my original post with that as well but stopped here along the way.
Hope this helps someone in their journey -- the performance with Windows 10 is significantly better than it was with Windows 7 in VirtualDub
. I'm sure drivers played a factor.