A feedback from my original post in this thread.
Rather than mess about with a 11 year old Onkyo subwoofer/receiver that may not work with Sky Q, I decided to spend a bit more and upgrade for the guest room too. After all, the TV and the BD player going in there are less than 18 months old and I am getting a Sky Q mini-box and Marantz CD6006 there too.
I decided to get a Pioneer VSX 333 Receiver and Cambridge Audio x200 subwoofer with a pair of Minx Min 22 speakers (2.1 best possible for that room). I should be able to get good audio from all sources then, including TV resourced programmes via Optical out. I'll use RCA-RCA connection for the Marantz, thus enabling its own superb DAC. The Pioneer even has a dedicated Phono input for my record player.
Does that sound OK?