Processor question

ghdprentice...I appreciate your post, but I have one room which is being used for both. I'd guess processors have gotten a smidge better in the 20 years since you stopped. I am a bit curious as to why I've had two responses to my OP, that advocate only two channel. I get it....but why post that here as it is non responsive to my question. 
  I do thank you both for sharing your agenda with me though.
     Steven

I have not heard either, but I have done a lot of reading on them.  Based on what I've gathered, I think the Maestro X9 might be suited a little bit better for HT/movies.  The consensus is that it sounds very good, but the flexiblity on configuration is not the best.  For example, you can only set on bass cutoff frequency for all "SMALL" speakers instead of assigned a different cutoff for each set such as left/right, center, surround.  If this doesn't bother you, I might tilt a little more towards the Maestro.

The McIntosh looks awsome, but I think it might be a just a little bit warmer sounding and more forgiving of bad electronics / source content.  I can't say for sure, but that's what I gleam.  The McIntosh might be just a bit better for music, depending on what your tastes are in type of sound.

For speaker’s calibration,
Audio Control Maestro X9  has Dirac Live  
McIntosh MX 123  has Audyssey MultEQ® XT32

I have read that Dirac is hard to beat.

i have a mcintosh mx132 and mcintosh mc602 as a stereo setup! i have it mated to 4 bose 901 seies 2 speakers. when i watch a movie and turn up the volume it sounds great to me!!!

I think folks like me look  to help with the situations greatest opportunity. Our experience immediately identifies the pitfalls of stereo audio in a home theater situation. So we try and be helpful. If separate systems cannot be done, then I can’t help with the question.