I also found out (although I'm not 100% sure how this works when you have several devices using the same module, I'm guessing index=2,3 might work) that you can set the index numbers in /etc/modprobe.conf, which is a much cleaner solution than messing with udev rules.
options snd-ens1370 index=0 options snd-sonicvibes index=1
I'll wiki this when I've had more time and hardware to test it with.
Have a look at http://www.wlug.org.nz/AlsaNotes under Not all sound devices work. Basically the index is a bitmask of acceptable positions. If you specify 0, 1, 2, 4, 8 etc it will lock it down. If you specify 15 it means it can pick. Often the problem is if you have a sound card already taking the first slot and then you say index=0 it can't do anything and gives up... -- Ian McDonald Web: http://wand.net.nz/~iam4 Blog: http://imcdnzl.blogspot.com WAND Network Research Group Department of Computer Science University of Waikato New Zealand