Hi, so I'm really trying to get my bass setup with garageband on my macbook pro, but the thing is whenever I try to plug in to the computer from my bass (using a modified amp cable with 1/4' jack on one end and a 1/8' on the other) I'm just not getting any sound. And when I say there's no sound, I mean that to be true for everything. Youtube, music, whatever. The cable just mutes my computer entirely when it's plugged in so I know it must be something with my audio input but I honestly have no idea what to do. I've made sure the monitor is "on" in the GB settings as I know that is a common solution, but nothing I seem to do works. Also please bear in mind that I don't have any mixers of any kind, I'm just trying to get my amp to go from my pre amp directly into the computer. Can anyone please help me?