King Zick

Have you looked at getting a Lanzar Opti6000D? I heard you can get them cheaper then the choices above and it puts out rated. http://forum.realmofexcursion.com/ampguts/35093-lanzar-opti6000d-guts-3.html

I doubt you would want 4 amps for daily use. IMHO, I think the Sundowns would be the best option. Less chance of 2 amps failing vs four. I realize they are refurbished but you shouldn't have an issue. How much RMS are you going for? The 4 Crescendo's will put out more power...