I compared USB input into my RME ADI-2 Pro vs SPDIF via the Allo DigiOne and RPi.(*) The USB on the RME is supposed to be immune to noise etc. Yet I'm convinced the SPDIF is better. Bizarre.
How frustrating to be an.... audiophile.
(*) Why? I was thinking I will sell the Allo. I don't "really" need it. I guess it stays. Mal you better get yours set up!