Sony STR-DN1080 Manual page 35

If you are not using surround back speakers or height/overhead speakers, you can connect
additional front B speakers to the SPEAKERS SURROUND BACK/HEIGHT terminals.
Connect each speaker as illustrated below.
Before connecting cables, be sure to disconnect the AC power cord (mains lead).
For details on how to connect speaker cables to the receiver, see "How to connect speaker
cables."
Monaural audio cable (not supplied)
Speaker cable (not supplied)
After you have made the front B speaker connection, set [Surround Back Speaker Assign] to
[Front B] in the [Speaker Settings] menu.
You can select the front speaker system you want to use by pressing SPEAKERS on the
receiver.
Note
After you have installed and connected your speakers, be sure to select the speaker pattern you
want using [Speaker Pattern] in the [Speaker Settings] menu.
You can only set [Surround Back Speaker Assign] if the speaker pattern is set to a setting that does
not have surround back and height/overhead speakers.
[26] Preparation 2. Connecting speakers
Connecting 2.1-channel speaker system to enjoy the
Front Surround mode
Connect each speaker as illustrated below.
Before connecting cables, be sure to disconnect the AC power cord (mains lead).
For details on how to connect speaker cables to the receiver, see "How to connect speaker
cables."