In the next update it is possible to disable a MIDI input port, which is very useful when you have two music applications running at the same time, or if you are using loopback/IAC devices. Unfortunately, there isn’t yet a UI for this, but if you’re comfortable editing an XML file then all you will need to do is change the following in the preferences.xml file:
<disabledInputDevices>
<type>string</type>
<value>Device name 1,Device name 2</value>
</disabledInputDevices>