Yup. Don’t do that. Splitter cables are intended to have one driving device (BV *or* BS9000) and two speakers. A switch box — common manufacturers are Almando and OneRemote.dk — will use either the presence of the Powerlink “Power” pin or the audio signal to switch your speakers back and forth. (There is a technical answer that I just don’t remember about how line output impedance of the source and RCA line input impedance of the speaker[‘s built-in amplifier] are supposed to relate, and what happens if you put another source on that Y in parallel with the speaker, thus the original source “sees” the wrong impedance, not just a speaker or two.)
P.S. Don’t throw away that splitter cable — you’ll need it because the Powerlink switch boxes only have a single DIN-8 jack output!
P.P.S. The true B&O-heads here will tell you that you ought to be running a MasterLink cable between those two sources, for an integrated setup. One remote, speakers connected to one device, automated source switching thru it, routing the IR remote commands — totally B&O-whole-house-cool! But the switch boxes work with *any* two sources and don’t require learning anything about B&O systems’ “Option” settings. Given that you started with a simple Y cable, I suggested the easier-to-understand method. But it is sub-optimal if you could get MasterLink configured instead: both your BS9000 and BV9 support it!
.
