I use a Motu 8A, with Roon running on windows. It works great with one caveat: if the sample rate of the source material doesn’t match the sample rate of the last track played, Roon loses control of the Dac. You have to push play a second time (which makes Motu change its sample rate to that of the new source material).
For simplicity, I’ve fixed the sample rate of the Motu to 96kHz and upsample or downsample all sources to 96kHz in Roon. One added benefit of Motu is that it’s a studio mixer. I’ve also hooked up my home theatre and another couple of analogue sources as inputs. I don’t have to worry about switching sources.The Dac will just play whatever source is coming in (or two or three sources at the same time if that’s what you want).
My crossover DSP is calculated through Audiolense for optimal time alignment of all drivers.
Just a warning Motu doesn’t seem to work if Roon runs on Linux (no driver).