Aphex IN2 - Manual (Page 6)

You should now see signal on the input and output meters and hear yourself in
the IN2 headphones or speakers.
Avid Pro Tools
Launch Pro Tools and create a blank session.
Click the arrow next to Session Parameters and the window will expand to show
Audio File Type, Sample Rate, etc.
Select a Sample Rate and for I/O settings select Stereo Mix.
Give your session a name and location and click Save.
Go to Setup-Playback Engine.
Use the top dropdown menu to select IN2.
Selecting this playback engine will automatically save and close your session.
Click Yes.
Click OK and your session will close and reopen.
Go back to Setup-Playback Engine.
Set H/W buffer size to 64 samples and click OK.
Go to Setup-I/O.
Click the Input tab. Select the current path and click Delete Path.
Click Default.
The path will now show IN2 Analog 1-2, IN2 S/PDIF 1-2.
Click the Output tab. Select the current path and click Delete Path.
Click Delete on the popup window.
Click Default.
The path will now show IN2 Analog 1-2, IN2 S/PDIF 1-2.
Click OK.
Go to Track-New.
Create 1 Mono Audio Track in Samples and click Create.
Click the red circle (Track Arm) on your track.