I have an older unit, M34SB, so the balanced OUT is not an option for me. As for input, with all of the usual disclaimers, in my system, with my gear, for my tastes, etc, at one point I made a comparision using identical cables (brand, length, etc) between Coax and AES/EBU, and in my system, the AES/EBU connection was clearly superior. JO has told me that Coax is superior, and in truth that is what I wanted to hear........it just didn't work out that way.