The "output" are the sub connection also. You can use both A, B and the RCA center is fixed. You cannot use both XLR and RCA outputs. The signal will drop off the RCA side vs XLR when the demand is low. That has been my experience with Mcintosh on more than one occasion.
The outputs go to your power amps, or can pass-through an AV if it have the option. Either way, through the AV or the Stereo unit..
All of the inputs are adjustable to maintain a "SAME" volume, switching from one source, to the next..
A very nice unit all in all. I've been using a C70 with select Telefunken tubes. I let the unit break in on stock tubes then switched.. It is a REAL keeper with the new tubes.
There is "different" than Mcintosh, to many that = better. I just picked a brand and went with it.