"Balanced audio is carried on a pair of wires, neither of which is grounded; the lines being driven with equal voltage, but each with opposite polarity"
"An unbalanced line uses one wire for the signal and another for the ground. Unlike balanced lines, unbalanced lines use the ground for signal return. In typical unbalanced cables, the ground is the cable shield."
got that from a quick search.
The EMU has a headphone amp with dedicated volume control. The Main Live level output does not have a volume control as I mentioned before, but yes, that will be your line out as such.
You would use the Main outputs of the 0202 to connect to your external amp. There are two options for this. One is to use the TS connectors, convert them to RCA using a TS->RCA converter cable
or use a converter with RCA cable cable.
Or you can use a regular mini-mini
or mini-RCA connector since the 0202 has both.
As for comparisons, I personally havent heard the Edirol, so I really can't comment on how good it is. But I do remember considering it when I bought the 0202, and I chose the 0202 in the end based on my research.