The fact that there is no difference when the EP0 is unplugged is very telling (as it influences a lot the power intake).

An active sub is one that has its own amplifier. The EP0 relies on the Audiobytes' amp for power.

With the last info you provided, it is better to wait for Axiom. Are you using the same cables and connectors? One could be sligthly dammaged?

See Mojo's signature