When I insert Cakewalk TTS soft synth I can preview midi clips with one click, but I want to use my SD-50 in the same way. Can I patch the SD-50 in the Synth rack and preview midi clips with one click through the SD-50 or do I have to keep copying the clips to the track pane in the SD-50 assigned track ? How would I assign the media browser window to recognize the SD 50 and direct the midi signal midi out to the SD 50
 
Herb
I love used guitars.  

I don't think you can. You have to have a MIDI track setup with the MIDI interface as the output. the Help Menu says "Unlike audio loops, MIDI groove clips require a soft synth or instrument track to play through."