They use (or used to use) an m-audio 1010LT by default--about the size of a Pulsar1 with a bunch of RCA's hanging off. I think the focusrite stuff is an option too but since that's firewire it doesn't really answer internal clearance issues. The other potential issue (aside from internal clearances) would be their choice of motherboards. I seem to recall the initial AMD based setup used a less than stellar chipset, but I believe they even have an intel based version now (?).
Just wanted you to know that I got it up and running smoothly at the moment! It's been rock solid since a detailed surgery, removing unused boards (incl Delta 1010) and moving the others around, then formatting and tweaking settings...
