Have you considered PS Audio's GCC series control amps? In the pre-owned market, it is within your price range. I'm using 2 GCC-500's to drive B&W 803D's with stunning 2 channel results. (See my virtual system) Paradigm Studio 100's should be comparable.
When I was auditioning, 803D's and Studio 100's were in the same room. I chose 803D's because they sounded more natural as compared to the 100's. But the 100's were very close, and had I not heard the 803D's, I probably would have purchased the 100's.
PS Audio GCC's have HT bypass, are built like the proverbial tank, and sound wonderful. Only, they need a fair amount of burn-in time; around 200 hours to fully appreciate their potential. I'm approaching that threshold now, and can state without reservation that they keep sounding better all the time. In addition, If, in the future, you want to "up the ante," there are some incredible mods that can be performed. I've yet to have them done since I'm really enjoying the stock units.