I have no personal experience with the EP Zero (nor the Audiobytes), but I found this comment from one of the PC World sites both relevant and useful:

"Dual 6.5in drivers in the subwoofer allow response to be somewhat uniform. The end result of this is that bass response is tight rather than booming. If you’re looking for a bass-heavy system you might want to look elsewhere, but if you can appreciate a system that exposes nuance and detail within music then this could be the right option."