Ken,
My primary integrated is a Musical Fidlity M5si and the secondary is an NAD 316BEE (original version). The connection between the two is Fixed Line Out from the MF into any of the analog input pairs on the NAD.
Cable is a WBC Mogami 2964, just a few feet long.
I'm thinking that maybe when the NAD is in standby it might be shorting, or nearly shorting, its inputs. Which would then be doing the same thing to the Fixed line out on the MF.
Other discussions I've seen on this topic seem to indicate that connecting a fixed line out to an input on another unit will sometimes work and other times not, depending on how the input and output circuits are designed on the two integrated amps/receivers involved.
I supposed I could just turn on the NAD even if I don't want to listen in the other room, since standby mode seems to be causing the issue.
Greg