Sony STR-DN1080 Manual page 26

[15] Preparation 1. Installing speakers
Installing 5.1-channel speaker system with bi-amplifier
connection
You can enhance the sound quality of the front speakers by separately connecting the built-in
amplifiers to tweeters and woofers in a bi-amplifier configuration.
30°
100° - 120°
Hint
As the subwoofer does not emit highly directional signals, you can place it wherever you want.
[16] Preparation 1. Installing speakers
Installing 5.1-channel speaker system with front B
speaker connection
If you have an additional front speaker system, connect it to SPEAKERS SURROUND
BACK/HEIGHT terminals.
You can output sound from either front A speakers or front B speakers, or both front A speakers
and front B speakers.