We are working on the finishing touches of a new theater with 6 zones of audio. The theater has a Yamaha RX-A830 fed to an Episode 12 channel amp. The place is small so the plan is to only run in Party Mode. When in party mode, everything is in synch, but the zone2 volume is way lower and cannot be adjusted. If we run it in zone2 (not party mode), we cannot adjust zone2 volume. If I change it over to regular audio out (not zone 2) then we have plenty of volume, but it is no longer in synch. Is there no way to adjust the zone 2 volume with external amp?