I'm a dealer of both & can tell you that these speakers are very very different from each other.
What RBH 661 SE/R gives you: Great music performance out of a traditional, furniture grade speaker. Excelent sound quality & solid imaging. Very nice all-around speaker.
What the Klipsch KL-650-THX gives you: Excellent, top shelf movie performance. Good/serviceable for casual music. A speaker better heard & not seen. Fantastic Horizontal (90 degrees) & Vertical (60 degrees) sound field offering an extremely high & wide sound stage. Top shelf dynamics. Designed with a purpose: Theatre.
Without seeing or knowing ANY of the other very important details about your specific needs, room, usage, setup, etc. I would sum it up like this....
In a family room (aesthetics play a roll here): RBH
For Music Lover: RBH
For Movie Lover where aesthetics play NO roll: Klipsch