"If you need to control external devices with MIDI *AND* use soft synths, you should uncheck the aforementioned box in the MIDI dialog, and define the soft synths individually in the tracks right click menu. "

Exactly.
You have to assign a default device in MIDI Drivers area, but then you can assign synths per track using 'Right-Click - Port'.

Once that aforementioned box is ticked, it doesn't become the default and allow other drivers. It Reroutes 'ALL' MIDI to the DXI synth.
IMO they should include the word 'ALL' in that check box description. One A and a couple L's shouldn't cost much to implement.
smile
At least that's been my experience.

Make your sound your own!
.. I do not work here, but the benefits are still awesome