Best Dac/AMP for HE-400's?

I just got the HE-400's and I love them but they just don't get loud enough, i'm not much of an audiophile but I do listen to a LOT of music so, what soundcard or Dac/AMP should I get that would be better and improve these amazing headphones to the best of their ability, I'd like to get the best price to performance and dont want to spend to much money. So could you help me out please thanks!

Internal - ASUS Xonar Essence STX II

external - ASUS Xonar Essence One

             - Schiit Magni/Modi combo

             - Mayflower Objective 2 ODAC

Price range would help.  The  Schiit stack listed above runs about $200, and the O2 combo will run between $200 and $250 depending on if you DIY or not.  If those are in your price range, and you don't need a portable amp, then they are both good choices and would easily drive your HiFiMan cans.

SMSL SD793-II

Stereo 24bit, 92000khz through SPDIF (fiber optic/coaxial). Up to 250ohms supported.

I use this for both my ATH-AD500X and HE-400, and they power just fine. HE-400 doesn't require that much amp like the rest of the "audiophiles" would have you believe, unless you have terrible hearing, and it certainly doesn't justify a $300 dac/amp. Just get somewhere in the $70-$150 range.

 

HE-400i

Dac: Musical Fidelity V90-DAC 24-bit/96kHz with USB

Amp: Rega Ear

Works well for me.