I am in the very infantile stages of selecting my next "step up" up grade.
So you're lying on the floor kicking and screaming, "I want, I want, I want?" ;)
I agree with the others -- your current gear is pretty good. If you don't want to upgrade the speakers (consider some Focals with the Beryllium tweeters -- you'll love the resolution), have a look at your power. Are you using a conditioner of some kind, and good power cables? I have no experience with Harmonic Tech, but if they aren't giving you the resolution you want, consider some Morrow balanced interconnects -- they're pretty remarkable for a reasonably-priced cable.