Use the headphone jack on the IEMagni for now: Vega → RCA cable → IEMagni → Headphone cable
Amp choice: These range from clean solid state, to warmer solid state, and to tube amps. There are MANY amp choices and nuances. I recommend starting with the tread below. Beyond that you must try different setups to find what you like.
What brand/model of headphones do you own now?