I have recently become aware of these new(-ish) interfaces, which might be of interest to the HW community:
https://www.esi-audio.com/products/u86xt/ and
https://www.esi-audio.com/products/u168xt/.
The thing that attracted me to them is that they actually have
MORE outputs than they say they do.
The first one says it has 6 outputs; the second says it has 8. But in reality it's 8 and 10 respectively.
Each one has an
extra pair of outputs called "Mix output", which does exactly what it says on the tin.
In other words, you could use 3 pairs / 4 pairs of speakers from Outputs 1-6 / 1-8, plus a sub which takes a mix of everything.
And you don't even have to include the sub in the HW audio routing - simply plug your sub into the "Mix output" jack sockets.