Since Retro AS-1 and Unity DS-1 is Sound Manager compatible you will be using the PCI-324 Sound Manager driver for output. This can be custom installed from your Motu Audio Installer if you haven't already done so. In the Sound Control Panel, be sure to choose PCI-324 for both Sound In and Sound Out.

In the Configure Hardware Driver( this is the same as the PCI-324 Console) be sure to set the Samples per Buffer size to 512 or smaller such as 256. These settings work best with Retro AS-1.

In the Monitor Outputs Menu, be sure to select two outputs. I prefer Analog 1-2. These are the 2 outputs on the 2408 or 1224 that will be used by Sound Manager and Retro As-1 or Unity DS-1.

In FreeMIDI you must enable the Retro Driver or Unity Driver under FreeMIDI preferences. Now if you assign a MIDI track to Retro or Unity you should hear the output on Analog outputs 1-2 of your Motu Audio hardware.

If you do not see this driver as a choice in the FreeMIDI preferences window you need to find the FreeMIDI driver in the Retro or Unity Folder under another folder titled "Goodies" or "Extras". Drag this FreeMIDI driver to the FreeMIDI folder that exists in your System Folder. Restart the computer and and then check the FreeMIDI preferences window. You should now see it.