[madgt621]

correct me if I am mistaken. But PT9 MP requires an M Audio interface right?

So wouldn't it be better to just upgrade to PT9 with your PTLE serial from the 11R, and have the choice of any Core Audio interface? You can even still go with the C600 if you want.

I mean you can get a Fast Track C600 bundled with PT9 MP, (it usually comes with PTSE) and it will save you roughly $160, but not being tied to an interface is well worth that price.

I just don't see any reason to go M-Powered other than to cut costs. And though you save a bit of money, I think as a whole you would benefit much more with just going with PT9.

Also, the OP does not state how many simultaneous inputs he needs, so it's hard to say whether or not running the 11R via SPDIF into the C600 will alleviate the situation.