not sure i am following
the optical rendu by definition requires a fiber/optical input to feed it its digitized music signal... which it in turn converts back into electrical form, to be sent to the downstream dac via its usb output
so i am not sure how an opticalrendu can possibly be operated without an fiber media converter in front of it
another way of saying this is the defining difference between the optical rendu and its predecessor ultrarendu (or microrendu) is specifically the fact that it does the electrical-to-optical-and-then-back-to-electrical processing, in order to remove the electronically generated and transmitted noise from computer boards/chips, power supplies, network switches and so on...