I guess it could be a design thing, but more likely, the wiring on one is reversed. I would think they have to push and pull at the same time. Typically, when you put two subs facing one another, you can play with the phase (push/pull) to obtain optimum setting. But pushing *and* pulling on the same sub seems odd to me.


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Denon 4520, EPIC80/500/VP180 Speakers