Usually I recommend a Crown or QSC amp, but your speakers need pretty low wattage. So maybe this would work:
https://www.long-mcquade.com/1242/Pro_A ... lifier.htm
The prices are in CDN, but you get the idea. You'll need a splitter to convert the headphone output from your headphone amp to the 1/4 inch (TRS) or XLR connectors, but then you'll be off to the races. Don't be off put by the technical language, you just need a power amplifier that provides the right wattage at 8 ohms. Any more capacity you buy isn't going to get you better sound.
Those are pretty fancy speakers. You could definitely spend more money on a fancier amp, but I wouldn't. The low wattage requirements are a symbol of the quality of the speakers in my mind. I wouldn't have spent that much on a pair of monitors though!