Hi, Hopetown!
As Tino rightly said, the direct monitoring problem is entirely in Apple’s ballpark, I’m afraid, meaning there’s a fat chance we’re ever going to get it, as the iPad crowd don’t need it, and those are the guys Apple caters to these days, not creative professionals.
The only inconvenience for us Mac+RME users is, however, that DigiCheck can’t meter Nuendo’s output directly on the Mac.
To me personally, that sucks donkey!
But everything else, setting up a monitor mix or looping back DAW tracks to inputs, can be done quickly and easily with TotalMix. I actually prefer it to direct monitoring, and have the same workflow on my main production machine which is a PC.
Feel free to ask me if you run into problems setting up the routing for whatever you want to do.