Wow....you're alive Rob.
Would still love to know the answer to this question here.
Edit: The answer is simply that the prohormones (pre DHT metabolites) are used by the body as a standalone which means SOME of the precursors bind to the AR before conversion eliciting their response which is slightly different then the response of the target hormone, DHT.
This is why the different isomers have different "feels" to them.