Analog outputs interaction on Arcam CD92

I have an Arcam CD92 that provides 2 sets of single ended analog outputs so that it can send the same signal to two different amps.

I use this feature, and leave my 2 SS amps on all the time. The problem is that amps interact even when the volume is all the way down on the one not being used. The sound quality changes if the 2nd amp is turned off. Also the volume can be lowered if the second amp is on.

I assume it is an impedance summing problem, But I would think that the two outputs would be better isolated. Anyone have an explanation to this? RThanks for the help.