Yes, you can connect your TV box to a Surround Sound system using either a TOSlink cable or an HDMI cable. However, some programmes may not be available in Surround Sound.
Press the 
button on your remote control to find out whether the programme supports Surround Sound. You'll see a '[SS]' symbol in the programme description if it does.
When using Surround Sound, you will need to use the remote control for that system to control the volume.
How to connect your Surround Sound system to your BT TV box
Connecting with a TOSlink cable
- Connect the TOSlink cable between the S/PDIF socket on your TV box and the Digital Optical In port on your Surround Sound system
- To enable Surround Sound on your TV box, press the Home (or YouView) button on the remote control. Go to Settings > TV Signal & Quality > S/PDIF Audio Format and change from 'STEREO' to 'SURROUND'
Connecting with a HDMI cable
- Connect the HDMI cable between the HDMI socket on your TV box and the HDMI socket on your Surround Sound system
- To enable Surround Sound on your TV box, press the Home (or YouView) button on the remote control. Go to Settings > TV Signal & Quality > HDMI Audio Format and change from 'STEREO' to 'SURROUND'
- Enabling Surround Sound through HDMI will set your box volume to 100% and volume controls will be disabled. You'll have to adjust the volume on your Surround Sound system or TV
What is SPDIF / Optical out?
Optical out or SPDIF lets you connect your BT TV box to a 5.1 Dolby surround system.