The idea about 5-pin XLR on the back of MDAC actually comes from me, so I should probably explain why I wanted 5-pin instead of 4-pin.
For balanced headphone users, I can offer too fit a 5pin XLR (the 5pin XLR seems to be the standard for Balanced headphone use).
I wrote that it's used by
stereo microphones, particulary the higher-end ones.
For balanced headphones, there's no standard or even "common practice" when it comes to cabling or connectors. The only common denominator seems to be XLR.
- The dual 3-pin XLR (male!) comes from headphone.com (and their HeadRoom amp(s?)). You can't easily connect those to ie. unmodified MDAC without a 3-pin XLR(female)-XLR(female) convertor.
- Then there's a small 4-pin square-like connector used by some portable DAC+amp boxes, like the SR-71B.
- A lot of DIY setups use 4-pin XLRs or miniXLRs.
- I've seen people using all sorts of connectors, like small 1/8" TRRS jack, dual 1/4" TRS jacks, ...
The reason why I wanted to comply with the "stereo microphone" 5-pin XLR way is that I like generic solutions. The cable I bought has a shield, which I'd like to ground, but besides that - I want to have a fully-capable balanced stereo output not just for the headphones. I can imagine myself buying smaller desktop active speakers/monitors and connecting them (via a DIY-made 5-pin to dual 3-pin cable) to the "headphone" output on MDAC, so I could switch between those and the main amps+speakers using dummy front jack.
My current use case is headphones, but I don't want to be limited by the lack of ground if I ever need to use the socket for something else.
Plus, using 5-pin XLR (ground, L+, L-, R+, R-) is the best generic solution according to common sense. At least in cases where two 3-pin XLRs can't be fitted due to size restrictions.
That's basically the story behind 5-pin XLR on MDAC (unless John created a standard for balanced headphones using 5-pin female XLR plug).
I'm not John, but I believe that if you ask him nicely, he would offer the 4-pin socket variant as well, unless it's more complicated than leaving the ground unconnected. If not, then ... well, at least blame me, not him.
