When playing a record, you can often hear the sound directly from the needle. To check if anything is working, unplug your RCA cables from the phono box and see if you get a hum when touching the center pin. If not, something's wrong with the Edifier. Have you tried plugging it in to the other inputs? If this works, then do the same to the phono box input. If still nada, then maybe there is a broken connection in the turntable.
