Proud Owner Of Polk Lsi25 Speakers!

[Bango]

Ok, got them hooked up over the weekend. (God they're so sexxy looking!) When I turned it on, I used Black Hawk Down to check the sound. I noticed right away that something didn't sound right...it just sounded distorted or something...hard to explain as a Non-Audiophile. Could it be that they're just too much to handle for my onkyo TX-SR605? I mean they sound MUCH better than my old little satellites...but don't sound nearly as nice as when i listened to them at the previous owner's home. I even asked him if he had conditioned the walls or anything, he had said no. I think i'm either going to upgrade to the 805(or 806 if I can wait a little longer) or get one of these separate amps. I have the three front channels (LSi 25 x 2 and LSiC center channel) wired with 12 gauge MONSTER cable (I got the cable for free, not going to pay for it!) Any suggestions on what might be causing my issue?