I do use an adapter with my digital coax cable (Supra) into the Mojo. I bought this from Amazon - it is a Monoprice RCA to 3.5 mm mono. Works quite well and i can use any Digital Coax cable with RCA terminations. https://www.amazon.in/gp/aw/d/B01ACHA4UG/ref=ya_aw_oh_bia_dp?ie=UTF8&psc=1

I have a Cowon C2 and Sennheiser HD 598 / ATH M 50. I do not have any headphone amps. I am considering buying a Fiio E12. Will there be a considerable improvement in sound quality? Cowon with BBE already sounds great to my ears. Please advise. Is there another headphone amp (less than 150 $)...