I'm having an issue with running stereo CMBIs through the KIY 250/0 Y cable that may be related.
In addition to the 16" Y cable, I have the two single Binder to stereo male 3.5mm cables that ship with each body and a custom Schoeps single binder to dual male XLR. With each of the three cables and with two separate recorders the same problem persists: each channel outputs both mics. In other words, there is no stereo separation. I double checked the matrix on my recorder to rule that out. Went to my DAW, inverted the phase of one track, and I get a null.
Save for one CMBI body and cable, everything is newly purchased. I'm sending everything back to Redding tomorrow and will report back.