Emotiva A-100, $300 and done.
Innerfidelity states 2.4mW into 47ohm to reach 100dB with your speakers, this offers 250mW factory and 8500mW with jumpers!
There’s also the Monoprice tube headphone amp/pre with ESS Sabre DAC, which will give 1000mw, and the soon to be released Monolith headphone amp/pre with dual AKM 4493 DACs & Dual AAA-788 Modules.
Don’t care if you spend $3000, it won’t be worthwhile over these options.
Your headphones are $1000, it’s super silly to spend more on an amp than on your actual headphones. Even if you want to use it as a pre-amp, you don’t need to spend much to get one that sounds good either.