Thanks! Sure, will do some experimenting. Tying the shield of the balanced cable to the chassis seems to be the best practice.... I would expect its possible to connect just one GND pin at minidsp end (all channel grounds will be connected I expect) to signal GND at the other end, or Chassis GND at the amp end only would work too.
Now, this is not really related to the topic, but I noticed that on some pictures in the teardown thread that the metal tip of the xlr is tied to the shield of the internal cable . At least, it looks like this on the picture below
Well, it is not clear from the available pictures what happens to that shield later, but I am puzzled... So, if I use a shielded cable between the xlr connector and the amplifier board, where should I connect that shield?