And in case you don't find it easily, here's how to set Cthulhu up with SONAR.
How To Setup Cthulhu in SONAR 1. From the Insert menu, choose: Soft Synth > VST2 > Cthulhu
In the dialog box that pops up, tick: Midi source, synth track folder, first synth audio out, enable midi output, synth property page, recall assignable controls. Then click OK
2. Next Insert whatever soft synth you would like Cthulhu to play. I'll use True Pianos Cakewalk as an example, but you can use any: Insert > Soft synth > VST2 > True Pianos Cakewalk.
In the dialog box that pops up, tick: MIDI source, Synth track folder, First synth audio output, Synth property page, recall assignable controllers. Enable MIDI out does not need to be ticked. Now click OK.
You now have 2 folders, both containing a MIDI track and a synth track.
3. In the synth folder (True Pianos in this example), select the MIDI track. From the input drop down menu, choose your keyboard input. Now play some notes to make sure you have sound. Now from the same dropdown menu, change the input to Cthulhu 1 > MIDI Omni. You have now routed the output of Cthulhu to your soft synth.
4. IMPORTANT! MAKE SURE THAT THE INPUT ECHO BUTTON IS ACTIVE (BLUE) ON BOTH THE MIDI TRACK IN THE Synth FOLDER, AND THE MIDI TRACK IN THE Cthulhu FOLDER.
5. Select the MIDI track in the Cthulhu folder. Make sure its input is set to your keyboard in MIDI Omni mode using the drop down input menu.
6. If the Cthulhu VST property page isn't already open, click on its synth track icon to open it. You will see on the page a drop down entitled Chord Presets. Click on it and choose any preset. Now play a single note on the keyboard (still with the MIDI track in the Cthulhu folder selected, but with the Input Echo button activated on both MIDI tracks). You should hear the chosen arpeggio play. Note that you will also hear a tone generated by Cthulhu. This can be turned off using the speaker icon in its VST property page.
Now that you have it working, select both folders and the tracks using control-click, right click on the blue highlighted section of any of the selected tracks and choose "save as track template" from the dropdown menu and give it any name you like.
Next time you want to load it, just right click in empty space below your last track and choose 'insert from track template', then the name you saved. This will load both the soft synth and Cthulhu and set up all of the inputs and Outputs for you. You just click on the Cthulhu MIDI track and play away!