Equipment: Plugable USD Audio Adapter (headphone out/line[mic] in) and iMac macOS High Sierra
My old MacBook Pro (OSX 10.9.5) had a built-in headphone out port (3mm) and a mic/line in port (3mm). I used to use this to record from my Sibelius software (as playback) to GarageBand (to record) by taking a single 3mm audio cable and hooking one end to headphone out and the other end to mic/line in. It worked perfectly. The problem: I just bought a new iMac. There are no headphone or mic/line ports. I bought a single Plugable USB Audio Adapter that has a headphone out and a mic/line in. HOWEVER, if I try to plug my audio cable from the headphone out to the mic/line in GarageBand doesn’t hear it. Is the plugin only capable of using only ONE jack at a time? I.e., do I need to buy another to use ONE for headphone out and the OTHER for line/mic in? Or am I programming my internal mixer (output) and GarageBand’s input incorrectly.