I originally bought, with my wife's approval, my first Aneros massager from LH a few years ago closely followed by the Maximus for the "fuller feeling" The smaller Aneros always hit the sweet spot and I was able to have some stunning sessions. I did achieve a "Super O" which was unbelievable and if I'm honest quite frightening - I was thrashing around uncontrollably on the bed ala the Exorcist! I never managed to cum hands free with either Aneros, the Maximus always made me produce lots of pre-cum though.
After reading online of the ability to externally massage the prostate (at that time, there was no way my wife was going to stroke my prostate internally), trial and error led me to "my technique. Using 2 or 3 fingers I invert my flaccid penis back into my body (it helps that I'm a "grower" not a "shower"!!) and by gently making small circular motions I can stimulate my prostate. After 5 mins, I can sense the change internally and then my body starts to respond, buttocks tightening and small waves of pleasure sweep over my body, gradually the feelings intensify and my whole body becomes very sensitive (love pinching my nipples at this point). It's at this point that I stop for 10 mins and then start again ("edging" I suppose) - my prostate responds instantly and with more intensity.
Depending on circumstances I can do this for 1 hour +. I can either cum with my penis (flaccid) still inverted which is another great feeling or I wank myself to milk my prostate. My body remains sensitive the next day so it's quite easy to get the pleasure going again.
I hope that this has been of some interest and if any one has any questions then please ask.