Sounds like you've got your hands full. I wish you the best in your project and hope you can make it work to your satisfaction. Active multi-amping can be tough to dial in, but it can sound SOOOO nice : )
I ran a 2600 for a while with a set of Klipsch Heresy's. The "warm and smooth" NAD sound complimented the "hot" sound of the horns pretty well. While the 2600 is not a bad amp, it is not "commanding" enough on bottom end. I would sell both of those ( i see that the used prices on these have climbed up somewhat, making it a good time to unload them ) and look for either an Electron Kinetics Eagle, Perreaux PMF-3150, Robertson 6010, Aragon 4004, etc... These are all excellent "bang for the buck" amps when it comes to low frequency reproduction and impact. You might be able to find better amps for bottom end, but you'll be paying a LOT more for it too.
For top end, look for a Forte' 4 / 4A. Class A bias, 50 @ 8, 100 @ 4, etc... and sounds very sweet, airy and delicate. Trounces amps costing WAY more money with much bigger names.
Take these suggestions for what they are worth. That is, slightly less than what you paid for the advice : ) Sean