also, please put those subs in a transmission line box, they work in the Hooker Audio prefab about $150 each (they were built to Diamond Specs) or you can get the cut sheet from Diamond and build both for about $20, I have them for my Diamond Cm3's almost doubled spl(never been metered just seems like it) (trust me on this one).
what are the voice coil configuration on them subs? try a cadence zrs-9 if they are dual 4 ohm or a crossfire vr2000D if they are dual 2 ohm. the cadence makes full power at 1 ohm and the crossfire at 2 ohms. both very good amps.