Sony STR-DG720 - Manual (Page 16)

16 US
a)
If you have an additional front speaker system,
connect them to the SPEAKERS FRONT B
terminals. You can select the front speakers you
want to use with SPEAKERS (OFF/A/B) on the
front panel (page 28).
b)
If you connect only one surround back speaker,
connect it to the SPEAKERS SURROUND
BACK L terminals.
c)
When you connect a sub woofer with an auto
standby function, turn off the function when
watching movies. If the auto standby function is
set to on, it turns to standby mode automatically
based on the level of the input signal to a sub
woofer, then sound may not be output.