[sdiy] Best way to wire up a multi-channel cable?

[cheater cheater]

Hi all,
I want to create a cable that carries 16 channels of audio. The
connectors on each end have 20 pins each available, so not quite
enough to run balanced. My best guess is to run 16 channels
single-ended + reference, but I'm not sure how to best create the
transmitter and receiver such that EMI gets minimized. I was wondering
if someone was knowledgeable enough to point me in the right direction
towards technical materials that analyze this sort of situation, as I
bet it's something that's been done before.

The cables will be short - between 15cm and 50cm, with 2m being the
maximum - but I want to be able to retain good audio quality, prevent
ground loops, etc. This is a situation similar to a patch bay or a
modular synthesizer so while each run is short, total runs will be
long and will have loops in them as well as signals branching and
joining. Look at some examples of [complex modular
patches](https://www.google.com/search?q=complex+modular+patch&udm=2)
to know what I mean.

The one thing I was thinking of was:

- use pins 1-16 for each channel of audio
- use pin 17 to carry a reference voltage
- on the transmitter, take ground-referenced audio channels from the
internal circuits and add the voltage of pin 17 to them, then take
that summed output and put it out via the relevant pin (1-16). Call
the node with pin 17's voltage that is being added to all others the
"reference node".
- on the receiver, take input channels 1-16 and subtract pin 17 from
them. Again call pin 17 the reference node.

That can be done using a bunch of op amps, but my biggest concerns
are, as follows:
- loading down the reference node in the transmitter, and with
resistor or op amp differences, sending out channels (1-16) that are
each biased to a slightly different voltage.
- loading down the reference node in the receiver and component
differences as above, therefore recovering shifted versions of
channels 1-16.
- having high impedance on both input and output, making the cable an
antenna so it picks up EMI very easily

I would appreciate any suggestions.

Thanks!