I find this really dumb. This "surround processor" is known as a mid-side processor in the studio/production world. You can do this pretty easily in DSP if you have a DAC with enough outputs.
https://www.voxengo.com/product/msed/ this freebie plus some basic filters is all you need to recreate this device, should you so choose.
Anyway, the fact that DIY solutions exist isn't really the point.
This device really abuses the idea of actual surround sound, and IMO is too liberal in terms of messing with the original mix. I don't want what schiit thinks the song should sound like, I want what the band/producer/mixing engineer thought the song should sound like. Hard pass from me.