I just received the Real Tone Cable, it is perfectly recognized by Windows (I can record on FL Studio), however it is not detected by the game. I have all my other peripherals deactivated, put the cable in 48khz. I don't know what else to do, i've tried everything even nocablelauncher. 

I've got exactly the same problem, cable works fine outside the game but as soon as I load Rocksmith it stops working and the input shows as 0 volume and greyed out which I cant change. Did you ever get this solved?

 

Pretty late here. Mine wouldn't calibrate, for it to work I had to change my refresh rate from 240 down to 60hz, I know it sounds weird, but it's worth a shot.