Oops. I read the post wrong. I thought you were asking if you could take the rca OUTPUT from something else and connect it to the spdif input of the mbox. Sorry, never mind, nothing to see here.
Ok sweet. If the aux inputs are analogue, I would use the analogue outputs of the preamp and need leads with either 1/4 inch or xlr at one end and RCA at the other?
Ok sweet. If the aux inputs are analogue, I would use the analogue outputs of the preamp and need leads with either 1/4 inch or xlr at one end and RCA at the other?
Pretty much.
The thing to be aware of is that balanced signals carry very well over distance, and close to noise source, without picking up noise.
Unbalanced signals do not. Over a few feet it shouldn't matter but if you hear hums or buzzes on 5+6 you'll know that something nearby is interfering.
That's when you start turning off lights, moving power transformers around etc.