Nothing at all?
I have discovered that there are 3 status LEDs inside the unit. One seems to be for power and the other 2 for analogue output. If a digital output is engaged on the front panel, the 2 output LEDs go out. Strangely sometimes when the unit is powered up the output LEDs flicker rather than glow, and there is no analogue output. The old "switch it off and back on again" seems to eventually work, but obviously there is an issue to investigate somehow.
Interestingly the channel imbalance seems to have rectified itself.....
I like to think I am format agnostic, but this is the most engaging digital I've ever heard, in some ways out shining a PS Audio Direct Stream Jr. a couple of nights ago!