Please don't use this trick as your normal feedback method!
It is NOT a stable and intended way to create feedback,
since the delay is based on the buffer size of the audio setting,
which the timing in different devices can be totally different.
PLEASE USE the BUILD IN feedback module instead.
Story:
I was attempting to build a D flip flop without feedback module, something unusual happened:

Finding that somehow when 0A is triggered by a DC offset pulse, it manages to take a sample from 0D, send to 0B and flows back to 0D.
I was interested by this behavior, since Feedback should be done with the feedback module and this case doesn't have any.
Therefore, I try to recreate this behavior by using a simpler set up:
2 amps, 1 modulator, 1 module of your choice for forming a loop and a generator:
I set the modulator to phrase modulation, feeding a dc constant to the modulator,
and setting the mapping like shown.

It works, the signal is now feeding to the modulator and send back to the main amplifier, forming a loop without using feedback modules.
Then I was thinking, if this tricks works for only using modulator and amp, meaning that I may create a feedback using even older version of SunVox, Right? The answer is... Yes! I manage to create feedback effect using the SunVox 1.7.5, which has no feedback module:
(The pitch shifter is not necessary)

I will measure what the performance is and how stable for SunVox if using this approach to create feedback loops.
I will update this post if I can conclude the result by using this method.