Prohormones, if that's what you're referring to, are a waste IMO.
They may be just a "few steps up" the biosynthesis pathway for testosterone, but those "few steps" are regulated by the rate of enzymatic conversion. It's not as though there is any real shortage of androstenedione or any other "prohormone" in the body. Say you have a group of bricklayers building walls. If you dump truckloads and truckloads of bricks for them to use, this doesn't make them build more walls. They can still only go as fast as they can go. What little gains people may see with prohormones will usually be accompanied by equal sides, as these "prohormones" are just as easily converted to estrogens in most cases.
The sides:gains ratio is way too high for prohormones. Go ahead and ban them. They should be banned before AAS anyway.