Question

Matchbox pro 2010 i7 2.0, 8gig mem, never had this problem before. If I unplug USB after a few seconds it will function properly after it switches to built in audio.

 

I am using an AudioBox USB, not an i-Series. Owned this unit for at least 5 years. Tried both usb ports on my MacBook. Operating system is El Capitan. If I open iTunes and use the Audiobox USB as sound output, it will play through the monitors and then start to switch back and forth between the Audiobox and built in output.

Answer 1

Have you ever installed AudioBox drivers? The drivers will cause issues for AudioBox devices on OSX 10.11.

If you have installed the drivers please follow our uninstall guide:

http://support.presonus.com/entries/20353062-How-do-I-completely-remove-AudioBox-VSL-on-my-Mac-

If you have NOT installed the drivers and the AudioBox does not stay synced please partition your hard drive and reinstall OSX 10.11.  The head of PreSonus testing and QA covers why this is necessary here:

http://answers.presonus.com/2562/1818vsl-keeps-disappearing-configuring-device-studio-audio

Answer 2

Had the exact same issue. Solved it by connecting a usb-hub to the mac and then the Audiobox to the usb-hub.

audiobox ---> usb-hub ---> mac