I saw a stereo cable made by Kortwich (Berlin) to power a stereo pair from AC with 2 XLR-3 on each side: two F on mic side, two M on power unit side.
The L+R channels go into one of the XLR-3, only
one channel is used on this XLR-3, and a short cable carrying the other channel goes into the other XLR-3.
Two XLRs on each side instead of three, but you lose the possibility of adjusting the length of the cable..
Still better with short right angle XLRs.
From the outside diameter, I guess it was a "starquad cable".
http://www.filmtontechnik.de/en/products-from-kortwich/Expensive. Just buy the idea (which I saw on other sites as well).