So, I have been sniffing around for a bright box or tweeter box or some high Fq gizmo for my GK 800RB to run in biamp mode. So it just occurred to me, why not a center channel speaker? I bought a cheapo Klipsch Synergy C1 on ebay to see if it will work. I can cross it over pretty high so it won't stress it out. Maybe I'll get a better one if this works....... I can stick some velcro on it and stick it to the rat fur!! http://www.ebay.com/itm/Klipsch-Synergy-C1-Center-Channel-Speaker-Black-/131376386433?
It will appear to work fine until playing at gig levels and it fails. The problem is low (real world) power handling and low sensitivity. The concept is fine with the right speaker.