Using your high level/speaker connections using the avr's amps for zone, that would be separate from the main zone (or using an integrated amp/avr with the line outs on zone connections).
In my specific example I just used the main zone sub pre-out as I already had the transmitter and sub it matched up to in use in the workshop (main zone for that avr), just needed to carry the sub outside and was using same content as main zone in any case....I only need to worry about being in one place at a time