Was playing with the headphone controls, to replicate an effect I saw used to great effect on stage once - I was aiming to get the metronome click in the headphones, but not in the main output mix from EigenD, by lowering the main mixer drummer volume to zero, and setting the headphone drummer volume to something that only I can hear. It seems that the headphone volume is in series with the main volume rather than parallel, so reducing the main drummer volume makes it always inaudible over the headphones too.
The effect I saw on stage was a live band playing a few repetitions of a song on their instrument as normal, and then being joined later by an Apple mac playing bass and percussion all without missing a beat. This was made possible by all the musicians receiving a click track on a set of in ear monitors.
Interestingly I'm sure I saw Finlay demo something like this on the interview he did for G4TV, in which he plays a few bars of synth and then fades in the EigenD drummer using the strip controller. Can he remember how this was accomplished?