depends on how much you take. if you get good conversion, you would have to take around 750-1000 mg's each day, spaced throughout the day.
the only bad part about dhea is not only does it convert (its a pro hormone) directly into testosterone, but it also can directly convert into estrogen, and an Aromatase inhibitor (ex: 6-oxo, atd, 6-bromo) is only going to prevent the test you have already, and w/e converts from the dhea from aromatizing into estrogen.
It will do nothing for the direct conversion into estrogen from the dhea. If you wanted to take something that would fight the negative effects of E while taking a high amount of dhea, you would need to take a s.e.r.m. (selective estrogen receptor modulator) like nolvadex (tamoxifen).
and then there is the issue of the body having enough of the enzymes to complete the conversion, after you run out of those, you just have excess dhea floating around in your system doing w/e dhea does.
but 750mg+ would be a dose to start at, and probably good for adding to a stack consisting of a dry, non aromatizing steroid. I would never recomend taking dhea by itself unless you are over 40, or have low test & levels of dhea. it's been shown to increase muscle mass in men over 40, and women also, at low dosages.
also at an effective dose for young men, it would cause hpta shut down of nat test, or if you are lucky enough, increase production due to the increase of estrogen due to it converting into E. this is where a serm would be awsome.
also, I've never seen anyone supplement dhea like this, so this is all hypothetical, but it does directly convert into testotsterone, or estrogen.
oh yea, the cost of taking 750+mg and nolva would be expensive, and for most, there are cheaper options that would have more reliable results.