** Sounding is typically an experience, either you love it, or you hate it. Some hate the idea and others find the idea of being penetrated into their penis more than a thrilling thought. These men experience it as a sexual pleasure.
With sounding you stimulate the urethra by penetrating it with dilators, which can give an exciting feeling. You can even reach the prostate this way. Part of the experience is about the actual feeling, but also the ultimate interest of the Dominant for the cock, certainly plays a part in the sensation. Just like watching the dilator disappear into the cock. The combination can be quite tingly and lead to an orgasm.
I have quite a bit of experience in sounding, but since it is a delicate area, complications can always arise. These are at your own risk. I do not take any responsibility for this. The same goes for penetration with strapon and a prostate massage.