Hi

I’m in the USA so don’t about your Sky +HD box. However, I can tell you that using optical you’ll only get stereo 2.0. You may be able to get compressed DD5.1 if your TV can pass it through. 

You’ll only get a form of Dolby Atmos if you use HDMI ARC. You get full Dolby Atmos if your TV has HDMI eARC .

Bottom-line is…a HDMI connection is (IMO) always the better route vs optical. 

Thanks for your reply , TV doesn't support Atmos unfortunately

Not sure I agree….you should be able to get Dolby Digital to be sent across optical, if your TV supports it. You may have challenges (worth testing, I’m not sure) with Dolby Digital Plus, as it used to not be supported, but is now. Just not sure if it fits on the available bandwidth of an optical cable. 

That minor correction, I’d agree with AjTrek1, if it’s at all possible, the HDMI ARC connection is preferable.

Might be worth looking at the HD Fury Arcana as a potential solution. There’s another competing product that I haven’t internalized mentally, made, I think, by Feintech or someone like that, which does similar pulling / creating the eARC signal off of a normal HDMI signal, before it enters your TV. I don’t think either of those solutions are cheap (like an HDMI switch with optical is), but certainly less expensive than purchasing a new TV set. 

Thanks Bruce , I've just bought the beam gen 2 and 2 One SL speakers as the kit , from the questions I posted on here like listening to the TV speakers instead of the beam I can simply disable CEC in the TV , so when it arrives I'll try the hdmi route , hopefully I'll get better sound watching a sky hd Dolby digital movie via HDMI than I would using the optical ! Thanks for all your help and replies !