Thanks for the hand-off Trip. Here we go back ot the OP question.
BS-9000 to BV-7 via ML.
BS-9000 to BL-5 via copper S/PDIF, and the speakers daisy chained.
BV-7 to BL-5 via fully wired PL.
NO 'crossover/synch' cable needed.
In this case the BeoLab 5's "see" the volume and source information coming down the data/display leads in the PL cable, for example "CD 3 Vol 42" In just the way that a BeoLab Penta used the data to drive its display. There is no need for the synch cable because the volume data is sent as a discreet data set, not just as 'up/down'. The 5's know that volume is set at '42'. Similarly, when (and only when) they see 'CD' to they check the digital input, and then switch over. There is in fact no tone control on the digital input.
In a B&O 'audio only' setup, you would make PL and S/PDIF connections to the BR-2/BS-9000; you ought to also be able to do the S/PDIF connection to BG-CD 4500/5500/6500/7000, with PL to the BeoMaster. Must always use fully wired PL.
The 'synch' cable is only used with a non B&O audio source. In this case a Beo4/5 issues vulume up/down commands and the 2 BL 5's negotiate with each other as to what 'number they should be on.
Soundproof, what exact setup were you trying?
Russ