I have two M-Audio Delta 1010s and was experiencing clicks when I had both of them enabled on my system. When I disabled either of the cards, the random clicks stopped.
I'm using Pro Tools M-Powered 7.0cs3. The software seems to recognize both cards, but my guess is Digidesign didn't test this configuration or they would have discovered the sync/clock issue that is probably causing the clicks I'm hearing. I haven't tried using an external clock though.
Gene
http://www.topsoundproductions.com
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