Well I ordered a Soundsend last week to try replacing my Axiim QHD (development seems to have stopped, and there are outstanding niggles). Unfortunately my plan was thwarted at the first hurdle. I don't have, want or need a centre speaker. The Soundsend supports Dolby Atmos and 2.0 / 2.1 / 3.0 / 3.1 / 5.1 / 7.1 / 5.1.2, yet there's no explicit 4.x on that list and in 5.1 mode it doesn't automatically mix the centre channel to front L/R as one might reasonably expect. The hardware is almost certainly capable of supporting a phantom centre so this seems like an oversight.

The other less serious issue is that it power cycles the speakers too aggressively. For example, pausing playback turns all the speakers off (Beolabs go red), when unpausing it takes seconds to turn them on again during which time there is no sound. It also happens while browsing apps on the TV. This isn't a great experience. I had a similar issue with the Axiim QHD but they fixed it after I sent them a video showing such behaviour. Again, I'm sure this is something that can be sorted out in the firmware.

I've reached out to answers@wisaassociation.org but not heard anything back yet so I will be returning the Soundsend for now. I hope this is useful for anyone in a similar situation.