Solid State Logic SSL 12 USB Audio Interface - Manual (Page 8)

Open up Pro Tools and go to the 'Setup' menu and choose 'Playback Engine...'.
Make sure that SSL 12 is selected as the 'Playback Engine' and that 'Default Output'
is Output 1-2 because these are the outputs that will be connected to your monitors.
Note: On Windows, ensure that 'Playback Engine' is set to 'SSL 12 ASIO' for the
best possible performance.
Front Panel Controls
Input Channels