i had the same experience happen to me with my infinity renaissance 90's, when i was buying speaker wire i wanted to get two identical sets so that they would sound the same so i spoke with the manufacturer before buying the wires and he told me that when you bi wire the current of your amp gets divided between the two wires and that only half the current would get to the woofers and half to the highs and he told me that he does not like to bi wire speakers, of course i did not believe him and bought the two sets of wires so that i could bi wire, well i have to say that the speakers had more detail and sounded clearer but they lost most of their dynamics and had no punch, i hated the sound of them, i too liked them better with a single wire, i though that maybe speakers that are harder to run ( need more current) like the ren 90's sound better with the single wire and maybe the manufacturer was right in that the current gets divided between the two wires when bi wired, then i added a second amp and bi amped the speakers and what a difference, they sound clear like when they where bi wired but now have all the punch and dynamics you could ask for, i could not believe the difference i was hearing, if i where you i would try to bi amp your speakers you won't believe the difference.
greg