tried the bi-amp thing. i think the best you can do is bi-wire, but that part did sound pretty good.
after one look at how close the speaker connections were on the back of the panel, I bailed on trying both single and bi-wire and went straight to bi-wire with A on the mid and tweeter and B on the woofers of Inifinity Alpha 50's. As of yet, I do not have a sub, but I'm getting some decent extension down there.
none of the reviews I've seen mentioned that it would take a hand the size and shape of ET's to be able to feed bare wire into the 2500.. buyers may want to make sure they have enough room in the back of their racks for some dead-in banana plugs. there's simply not enough room to bare wire the unit for speakers while it's in a rack. I had to disconnect the wires from the speaker side and build the connections with the receiver sitting on the coffee table, then feed the whole thing back into the rack, which is actually pretty open.
once fully assembled and "optimized" the 2500 did a really stunning job on Fifth Element (superbit), X-Men (first one), and Big Trouble in Little China...
I'm very happy with the investment (about $ 700 shipped at E-tronics) compared to the $ 400 Sony STR-DA995 it replaced.
