Software Synths in DP 4.1 or higher
Soft synths in DP 4.1 and later are used on Instrument Tracks.
In previous versions of DP, Software Synth plug-ins showed up on audio or aux track inserts. Now, to load a soft synth, go to: Project Menu > Add Track > Add Instrument Track and choose your soft synth. The synth you create will show up in the mixing board on a dedicated instrument track. Double-click on the insert to call up the plug-in window.
To send MIDI to this instrument, assign the output of a MIDI track to the desired instrument and channel (ex: MachFive-1-1).