Julian, the VP180 isn't bi-amped in any way. Paying $40 extra for two sets of terminals would simplify the process of having to re-wire the speaker to by-pass its internal crossover. The second set of terminals has no active function otherwise. No receiver has an actual bi-amp capability; what some of them term a bi-amp option is meaningless, as previously discussed.
If a mode such as DPLIIx is applied to 5-channel material, then portions of the content in the 4th and 5th side surround channels(the front channels aren't affected in any way)which should be imaged in back are extracted from those side surround channels and directed to the back surrounds. The effect can be quite worthwhile if there're at least a few feet behind the listening position for a rear sound field to form.
