That's funny, about 6 months ago I was running the Fluance av-htb with a onkyo 602 and thought it sounded pretty good. Then a deal came along on a pair of used Onix Rocket 550s that I couldn't refuse so I snatched them up and I can't put into words the sonic bliss these provide, WHAT AN IMPROVEMENT!
Since then the x-ls have come along and occupied the Bedroom HT. I compared the x-ls to the 550s (I know not fair considering the $ dif but what the heck) And I must say they hold their own against any speaker. Very smooth and detailed, I would venture to say they offer about 90% of the sound of the 550s for 1/5 the price IMO. Huge soundstage with nice depth and detail, fantastic imaging, and smooth. You will enjoy them very much, just pull a nike.
Now onto the xsub. I wanted a musical sub that could plunge fairly deep into the 20s hz range. Since so many advocate stereo subs and giving the 200$ pricetag on the xsub, how could I go wrong. The only way I can articulate my thoughts on these little tanks corner loaded is, HOLYCRAP! They hit with authority down to about 25hz and still energize the room down to about 20hz (and still shake the floor below that). You won't be able to stop smiling with this combo, I'll put money on it! If you want more info feel free to PM me.
JR