Best Amp to drive my Apogee Stages?

Please give more info on your system.
If you're going to use a balanced preamp, you can utilize a balanced amp to it's fullest potential.
If you have a sub(s), you can roll off the Stages at 80 hertz & make life much easier for the amp(s) driving the Stages.
I had the Mini Grand system with the Mini Dax. I had great results with Pass Aleph 2s on the Stages, and an Aragon 4004MKII on the subs.
If you have just the subs & no crossover, you can use filters like Vandersteen sells, to roll off the Stages.

1. The Rowland Model 5 & Model 7s are getting old.
I don't believe Rowland will want to support or repair them indefinitely. Older Model 5s & Model 7s have been through many thermal cycles - being turned on & off. The output transistors eventually fail & they are expensive to replace.
I'm not biased against Jeff Rowland. I own a Model 2 & I will not sell it anytime soon. It just sounds too good to me.
2. I own (7) Murano monoblocs. These are close in build to the Rowland 501s, they have the same B&O module. These will drive the Stages, the problem is a pair of Rowland 501s used are at least $3500.00, in good shape.
3. I'm going to suggest you try an Adcom 5500. I owned 2 of these and one will output 300 watts per channel to your Stages. They only cost around $550.00 used, you can buy an Adcom GFP 750 with the rest of your budget, and upgrade to any fully balanced amp later, the GFP 750 will be good enough to use with any amp already suggested..