My long Xbox microphone nightmare is over. (Off-Topic)
I think. [knock on wood]
Ever since I've gotten an Xbox One I've had trouble with my original Astros A40 headset and mixamp. Apparently, I'm not the only one. When, during all this, my A40s fell apart I thought about buying a replacement, but then I started reading too much and got interested in possibly something better to work with my old mixamp, piecing together my own solution out of better equipment. I got some great headphones and a separate mic, and they worked like a dream (with my PS4).
I can't tell you the hours I've spent testing and researching this. At PAX I was lucky enough to talk to one of the lead engineer guys at Astros. (Thanks, nscuDuncan, for being my sherpa that day.)
He told me that I wasn't alone, that a new Mixamp should fix the problem (because its firmware could be upgraded), and that part of the problem was that the original Mixamp was made for the 360. He also sold me a new Astros microphone cord--it's telling that they had to make a special version for the Xbox One at this late date.
It seems to work, folks, and I'm reminded that the audio in this game is freaking gorgeous.
BTW, one reason why the PS4 worked all along is that the chat audio came through the USB connection. The Astros guy told me about a newer Mixamp that's coming out soon that handles Xbox chat the same way. I asked why they can't make one Mixamp that works that way with both PS4 and the Xbox One, and he said because Microsoft wouldn't let them. Jerks.
Kermit