The RVX-42 is part of Klipsch's Reference Line. Klipsch has three different lines...the entry level Synergy product which is what you'll find at Circuit City/Best Buy, etc. The Reference line which has upgraded drivers, cabinets, crossovers, etc...and the THX Ultra 2 line which is one of the premier home theater speakers on the market...albeit at a price.
The RVX-42 is a pretty amazing little speaker and a multiple award winner. Considering its' size, it is extremely surprising how dynamic it is. As pointed out, you will need a subwoofer that crosses over a bit higher...though I've used it with an 80hz crossover without any issues. Given the close wall placement, it actually works very well. This, by the way, isn't any different than many "plasma format" speakers. What sets the RVX-42 apart from most of the breed is the fact it does go loud and isn't compressed. I've sold several sets and my clients are very happy with them.
"Did you make 'em fine-ass-soundin' speakers over there what would sound gooder than hell comin' out of the back of my truck-boat-truck?"
-Early Cuyler. Poet Liquoreate