I'm going to agree with sid about breakin; although I do recall some post where Ian said that there really was some amount of breakin, but only up to about 40 minutes of use. Beyond that, it is YOU changing, not the speaker.
Bub, I just think that is a really big room for those speakers, especially without a sub. And your placement sounds really problematic. Did you see how it sounds if you stand on a ladder? I don't think your receiver is the problem; HK makes good products.
Try fiddling with speaker placement - a lot. Don't put them inside an entertainment center if at all possible. Get them down so that they are firing level with listening position.
Based on the description you give, I can't help but think that the listening environment (especially the speaker placement) is a bigger problem than the electronics.
