– Make sure Symphony I/O is in “ProTools HD” AIM (Audio Interface Mode for ProTools HD, HD-Native, HDX) by pressing in and holding on the right-side front-panel encoder until it comes to the AIM menu. It should say “ProTools HD”… if it doesn’t, scroll through the menu until it does and then push in on the encoder again to select it. The Symphony I/O will power down and then restart in ProTools HD AIM.
– Make sure the Symphony I/O is connected to a ProTools HD (HD, HD-Native, or HDX) card and that you have installed the proper ProTools software.
– Make sure ProTools is NOT open. Also make sure any application you want to use is closed.
– Open Audio MIDI Setup (Applications> Utilities> Audio MIDI Setup) and select the ProTools hardware as the computer’s default output.
– Open up the desired application- for example, iTunes, play an audio file and you should see the ProTools CoreAudio driver open up and see/hear the output on the Symphony I/O.