Headphone amp? Which one?

I currently use a Scarlett 6i6 2nd gen audio interface and a pair of Beyerdynamic DT 990 PRO headphones. I can't get enough volume from my headphones while recording without cranking to the volume to nearly maximum. I'm wondering if a headphone amp will solve my issue and I would like to spend no more than $200, if possible.

Can anyone help me?

Interface Specs:

Frequency Response 20 Hz to 20 kHz, +/-0.5 dB Dynamic Range 108 dB (‘A’-weighted) THD+N < 0.001% Maximum Output Level (0 dBFS) +13 dBu, balanced

Headphone Specs:

NOMINAL SOUND PRESSURE LEVEL96 dB

250 OHM
 
I would recommend the NUX Mighty Plug Pro.
61f6jSPTTPL._AC_SL1500_.jpg