IIRC, the signal going to the amp is very low on certain BOSE systems. I think it was that with the regular BOSE, the volume of the signal going to the amp was controlled by the head unit, which changed the power on the signal wires much like an aftermarket amp would be when connected to the line-level input. On the LUX BOSE, the signals are low-level and are at a steady power level and the volume is controlled by a data BUS to the amp. He may be able to test the amp's inputs with a DVOM set on a range of VDC that coincides with his type of BOSE system.
Again, this is what I recall at the moment and it may not be (entirely) accurate.