Late 2013 Macbook Pro OS X 10.9.3 Maverick In sound preferences the only input device available is "internal mic". I have Audacity as well as Garage Band and I.Movie loaded. Mini jack works fine  as o/p but will not "see" any line level feeds (standard stereo jacks used). Also tried usb - no joy there.
Is there any inexpensive software around which will "wake up" the line - level input?
Macbooks don't use standard stereo trs jacks, they use '4 ring' jacks. Anything else is likely to just not make a firm connection - see MacBook owners frustrated by new audio jacks

You didn't give enough info re your USB attempts for me to guess. Edit your question to provide more info &amp; I'll see if I can modify this answer.