Actually you don't really need a "coax" cable, you just need a regular cable with an RCA interconnect on one end and a mini-jack on the other. Although coax cables are supposed to be 75 Ohm from point A to point B, many cheap ones actually aren't up to these specs. (https://www.head-fi.org/threads/can...oax-or-does-it-have-to-be-a-75ohm-one.563361/) The sound was passable. I would say USB is sharper, more defined and with more body. I have never used the optical input. I wouldn't recommend using a CD player and a regular cable from the coax digital output to the mini-jack of the Mojo unless that's your only option. In that case, go for it, and enjoy your CDs.