Skip all the conventional headphone amps. None of them will do it. What you're looking for is something that can drive speakers. For $600, I'd look for a used Crest CA2 on ebay. I don't think the Mini-X can touch this pro amp. I've had one before and was very please for paying $300. The only caveat is the loud fans which you can disconnect. For the loads you will be running, I think it can run passive. If not, you could always swap out the fans for low RPM Noctuas.