Bean,
IMO,
The SBM1 you are getting - it has the coax mod - right? So I am guessing that there is a coax out and the female seven pin that is built in. If you are getting a male 7pin to optical for the jb3, give the patchers the coax out from the sbm1. Don't attenuate your signal for the convienience of the patchers. Not trying to sounds like a dick, but your recording comes first. If they want the V3 adc signal, they can take it and then boost the levels in post.