Thank you! I appreciate it! I've read the thicccc Denon manual and the McIntosh MA5300 back to back but couldn't find much but I could've also missed something. Any info would be much appreciated
Manuals are often poorly written, I read the manual. I think you don't need to use the trigger cable to put the unit in pass through, you can just follow the instructions on page 19.
The trigger, is, as usual, used to remotely turn on a second device, in this case, the MC5300.
On page 3:
So, I think it mentions "stereo" because of the Meter illumination, not because of the pass through function. In that case, use a stereo cable and it should work. The Denon's wired as mono so it may not have the meter control function, depending on how the MA5300 is wired. The manual is not clear about this but you can contact McIntosh for more information. For now, I would bet either mono or stereo cable will work, but it is better to try a stereo one first.