Ok, now I tried opening AT, making sure the controller was checked, closed out of AT, opened Sonar, and it DID, this time, recognize the audio driver. Also, AT now shows up in devices!
I next reopened AT, made sure AT was receiving the MIDI signals, and pulled up Dimension Pro and set the MIDI input to AT. I loaded a preset and the MIDI data from my controller was detected, both in AT and the DP input.
However, I'm getting no sound. Could this be a Sonar issue - sometimes this happens without AT, and I forget the fix (for the no audio issue, despite proper routing)?