How to optimise the Roland MX-1's 'digital' channel (feat. Behringer RD-9 and Roland Integra 7)

Aaah, what to do with the confusing 'digital' channel on the feature-packed MX-1 mixer? Default solution is to run regular line level sources through an analogue-digital converter ... ok that's one way, but it's hardly making the most of the connectivity on offer. Here are a couple of other suggestions that will help you really make the most of the digital input channel, demonstrated with help from a Behringer RD-9 drum machine running through a digital-output equipped sub-mixer, and a powerful synth module (Roland Integrated 7) featuring a digital out.