Did you ever contact Orb about the differences in the Mod 1 and Mod 2 ?

Sounds like Orb wires these in parallel. Which creates the 4 ohm load that Orb states. This 4 ohm load requires a bit more current. Which probably explains why the level is not the same . If anything you probably had to increase the level to match the left and right.

Call Orb. They could explain it better. But I would imagine the scenario I stated is probably what they are going to tell you as well.