Hey mafikloster
the following link will help you:
ION Audio USB Turntables
1. Connect your ION USB turntable to a USB port on your computer, and power it on.
2. On your Mac, starting from the Finder, select the Gomenu at the top of screen, and choose Applications.
3. In the window that opens, double-click QuickTime Player.
4. At the top of the screen, select File > New Audio Recording.
5. In the window that opens, click the small arrow to the right of the round Record button to select your connected turntable as the audio device. It will appear as USB Audio Device (or similar). Now, sound from vinyl playing back on your turntable will play through your Mac's speakers (or another other selected audio output device if you have one).
6. Use the volume slider at the bottom of the window to control playback volume.
Have a nice day!