Try Oppo HA-2SE headphone amp ($299). Has all sorts of inputs including analog, S/Pdif and USB. I have earlier version (HA-2) and use it as stationary amplifier with my Mac Mini via USB and also as portable amp with my Samsung phone - also via USB. Sound is wonderful and build quality is top notch.
https://www.oppodigital.com/headphone-amplifier-ha-2SE/
https://www.oppodigital.com/headphone-amplifier-ha-2SE/

