@sweetjonnyp did you ever figure it out?. I have a Mcintosh C2500 with a two zone output configuration as well. Output 1 is a direct connection to my MC452 running a set of passive speakers and Output 2 is supplying a signal to a Sonos connect which is connected to two Hypex Ncore500 Monoblocks which in turn pick up my whole home audio setup. I will be very interested in finding out how the C2500 can achieve individual output volume control as you have mentioned (I realize we have different pre amps but the premise is the same)