It is my understanding that the first gain stage of the IO is single ended. Hence the reason it does not matter if the input is single ended or balanced. It could matter if an opamp was used on the balanced input but one leg is simply sent to ground, making it for all practical purposes identical to the single ended input. I do use the XLR input on my Eclipse but only because I think it is a better physical connection. There also may be an advantage in cable geometry with a balanced cable.
The original BAT phono stage also had a single ended input (the next two stages, like the IO, were balanced). Viktor K stated bringing in a balanced phono signal was not all positives. You could cancel differential noise but since you are using two wires for the signal (plus and minus) you are also bringing in twice as much inherent noise. At the time (15 years ago??) there might have been only one or two phono stages that were balanced end to end. I think the technology to use such a low voltage balanced signal properly was not easily available at the time.
Later (10 years ago??) BAT did implement a true balanced input, so Viktor did have a change of heart and was able to technically accomplish what he could not earlier. Apparently Jim White is still of the "old school" on a balanced input.
The original BAT phono stage also had a single ended input (the next two stages, like the IO, were balanced). Viktor K stated bringing in a balanced phono signal was not all positives. You could cancel differential noise but since you are using two wires for the signal (plus and minus) you are also bringing in twice as much inherent noise. At the time (15 years ago??) there might have been only one or two phono stages that were balanced end to end. I think the technology to use such a low voltage balanced signal properly was not easily available at the time.
Later (10 years ago??) BAT did implement a true balanced input, so Viktor did have a change of heart and was able to technically accomplish what he could not earlier. Apparently Jim White is still of the "old school" on a balanced input.