I made some test and saw that the phase is reversed.
I’ve checked the balanced cable I build with special RCA bought at the same time than the Tone2 Pro, and they are OK. I didn’t check with unbalanced RCA but it should be the same.
So I’d like to know if it can be fixed via a firmware update, or if I need to rebuild my cables and switching both signal points.
I didn’t test the Tone2 Pro via SPDIF yet, but I suspect that if this RCA is also reversed, it could mean that it will be the opposite of what is said in the manual, so with SPDIF OUT (not available now) usable with a standard RCA cable, and SPDIF IN usable with the special cable (with one balanced RCA)