I do use Raspberry, but it's no comparison with functionality of BlueOS or Matrix where everything is nicely integrated - for instance when you change volume in Roon, it gets changed on the device and you can next change it with remote. Nice display (and I mean "nice") is really important as well.I can do all of this with my Raspberry Pi running MoOde with camillaDSP. What we need is more multichannel DACs like the Topping DM7.
A 4 channel DAC would be useful for subwoofer integration. They could even implement a simple high and low pass filter on the device itself.
Bottom line is I don't want to spend 1000 hours tuning my custom solution to get messy setup of 5 boxes, I need something I can just put there on my sideboard and enjoy. Something my wife wound't complain about using.