+1 All great recommendations by
@Count Arthur
$100 today buys you any one of those excellent amps - leaving $$ to put toward where it really makes a difference - your Headphones.
Suggest do some research before buy. A decision point will be closed (like your HyperX appears to be?) And Planar magnetic, or conventional voice coil. A good place to browse is
@solderdude site:
https://diyaudioheaven.wordpress.com/
I have the Liquid Spark and am quite happy with it with my HE400i phones. Good build quality, plenty of power. Doesn't measure as well as some others, and not a lot of Love around here for it, but IMO underrated.
Have fun!