Small budget :
https://www.sweetwater.com/store/detail/HP4E--akg-hp4e-4-ch-headphone-amplifier
Medium budget:
https://www.sweetwater.com/store/detail/CAN22H--cranborne-audio-n22h-headphone-amp-and-cast-breakout-box
Those two look good, your ears will adjust to either amp and you can then make your listening decisions.