Well, that sentence doesn't make a lot of sense to me. The Main A and Main B speakers on a Z1 would typically go to two sets of front speakers, or perhaps be setup to biamp the front speakers (for no real reason).
You can pull all the other amplified channels off your Z1 and just run the 'A' speakers, then just run the 'B' speakers by themselves to see where exactly they go. But, my expectation is that they both go to your front left and right main speakers.
If you look at your front speakers, they may have two sets of wires run into them.
But, at the end of the day, we can't tell you precisely where the wires in your home are going to and what they power. It could be a set of speakers in another room for all we know. It's just not possible for anyone but you to determine that. But, if it were me, I would disconnect all the other wiring, being VERY CAREFUL as to label every wire so I wasn't confused in the future about where it belonged. Then I would test just the A and B speakers by themselves.