I've a 20 Hz modulation in my synthesizers ...  Strobe 2  and,  I discovered, probably in others as well.   I know not where it is being generated.  I suspect  that somewhere in my SONAR Platinum.  Here is a link to the waveform audios (wave files) as well as screen shots (jpegs) to help diagnose the issue.
 
Any help is most welcomed!

I would expect this to be due to a setting in the synth rather than the host. 
To confirm it is not from SONAR, try the synth in one of the many free VST hosts available.
 
https://www.kvraudio.com/product/vsthost-by-hermann-seib
 
 

 
 
Thanks for the suggestion.  I didn't succeed in trying out the Synthesizer using another DAW ; but, I did exercise the Audio channel  with no MIDI Synthesizer using True Piano.  No Key Studio Input  ... i.e., just using the virtual keyboard in True Piano.    I recorded the waveform  and heard that the 20 Hz modulation  was still present. So it is something, I suspect,  that is implicit in my SONAR Platinum setup. I am not terribly knowledgeable about all the ins and outs of Platinum but I must have some parameter screwed up.
 
I've added the TRUE PIANO Waveforms to the Link cited above. The modulation, as you might see, is one of there being no audio out for 10 milliseconds  at the 20 Hz rate. It is doubtful; but, could it have something to do with latency?    

I increased the buffer size from  fast at 10 ms to 50 ms and the problem vanished.

Are you using ASIO or WDM driver mode?  Looks like you might have to increase the number of audio buffers or even update your audio interface drivers.

Thanks.  I increased the buffer size and the problem went away.  Now I just need to adjust it to reduce the latency as I  hit a  Key Studio note  and await the audio to create sound!