Yamaha RX-V673 Owner's Manual page 76

Enjoying the same source in multiple
rooms (party mode)
(RX-V773 only)
The party mode allows you to play back in Zone2 the same music
that is being played back in the main zone. During the party mode,
stereo playback is automatically selected for all zones. Utilize this
function when you want to use main zone music as background
music for a house party.
Press PARTY.
Each time you press the key, the party mode is turned on or
off.
When the party mode is turned on, "PARTY" lights up in the
front display.
• If the party mode does not work on Zone2, set "Party Mode Set" (p.100) in
the "Setup" menu to "Enable" (default).
PLAYBACK • Playing back musicin multiple rooms(multi-zone) En 76