As you say you need to connect the UHD box directly to the TV via HDMI to benefit from 4K UHD resolution. Many modern A/V receivers do support 4K UHD but if anybody is thinking about buying one please check that it supports HDMI 2.0 and HDCP 2.2. Also note some A/V receivers only support 4K HDR on one or two inputs which may not be enough if you want to use BT UHD and also a UHD Blu Ray player, say. For example, the Pioneer SC-LX89 has 8 HDMI inputs but only three support 4K with HDMI 2.0 and HDCP 2.2, although this is sufficient for most.
To address your problem, there are three possible causes:
1. The TV may only support 2.0 over HDMI ARC and S/PDIF even though ARC allows Dolby Digital 5.1.
2. The TV may only accept stereo audio via its HDMI input and may be negotiating this via the HDMI handshake when connected. In this case the YouView box will just output stereo.
3. The TV may be configured to output stereo via its Audio Out (including optical output). You can check this in the TV's Settings under Audio Out. From your post this seems unlikely as you have 5.1 audio working via ARC but do please check.
Can you get 5.1 from your YouView box via the TV for any content? Try FreeView HD (e.g. a 5.1 film) and a BT Extra TV Multicast HD channel too.
For reference, note BT use Dolby Digital Plus (E-AC3) for 5.1 surround sound on the multicast channels while Freeview HD broadcasts use HE-AAC audio. Both can be carried over HDMI ARC, providing your TV supports it, but both require transcoding to Dolby Digital (AC3) for carriage over optical S/PDIF. I'd expect the TV to be able to do this but some can't.
|BT TV expert||PaulSk|
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