Great review MLE!
I like the term
"absolute comfort legend".
I personally thought the Anniversaries were more fun and immersive for gaming as they had greater body and were more grounded sounding. The MA900s sounded a tad thin and floaty. I do think MA900 is a more immersive than the Q701 in terms of signature, but not quite on par with the greater bodied Anniversary. Another thing I noticed with them being so open is that they seem to lack some of the decay, reverb, and ambience of "sealed" headphones - which detracted from their immersion some. Less ambience meant I felt a bit more detachment from the physical spaces and rooms in a game. I agree that the mids are a highlight on the MA900, but I personally found them to be a bit
too much of a focus. The X1s achieve a fun and immersive sound by pushing their mids back just a bit to open up room for other things and create some of that "U" shaped home theater sound. The MA900s have more difficulty with that as the mids are always forward, always clear sounding, and can't be ignored. I think too much midrange can hurt immersion in the same way that too much bass can hurt competitive gaming.
It could be some of the grain gets abrasive sounding, but I think there was actually a bit of glare somewhere too. There was a specific spot that would jump out louder than on my other headphones and would sometimes limit how loud I could turn up the MA900.
The Q701 has drier peakier mids than the Anniversary, which in turn has drier peakier mids than the K712. The main issue with the Q701s timbre is the mids being a bit too thin and dry. The Anniversary fixes that some and gives them greater body and smoothness. The K712 takes it slightly further, but not too much. I personally prefer the timbre on both the Anniversary and K712 to the Q701. Between the Anniversary and K712, a slight edge to the K712.
The K712 doesn't change the soundstage too much. I think it will still be oval shaped. I can't remember the AD700s soundstage depth. I thought the MA900 was oval shaped too. Depth is tricky to pull of. The T1s and HD800s had nice depth
I doubt you will have any problems as the mic will be out
in front, not
behind the headphones where leakage is the highest.