Unfortunately it is nearly impossible to describe any sensation we have. The DL2000 pulse is a very unique physical sensation between an electrical impulse and a physical impact.
It depends on whether your setup to shock in the penis or around the scrotum, which in turn is a function of what chastity cage model you use. If you use the CB3000 - the standard model described in this website - the shock impact is supposed to feel like a strong slap. I have not personally tried it. I use a Mature Metal custom made model which is specially adapted to the Dreamlover. In this case the shock is mostly felt around the ring that stays between your body and your balls. I would describe that as an intense burning and vibrating sensation, which is not pleasant at all, but leaves absolutely no marks on the skin. The pain, while intense, fades away almost instantaneously after the pulse stops.