Old Brown Java - Challenging But Outstanding Espresso

We experimented with Old Brown Java and what a coffee it is; however the challenge is setting the grinder up correctly. If you're thinking of using this great coffee place, close attention to the speed at which the coffee is flowing through the ground coffee. The grinder settings are completely different to any other coffee I know. 

Once right the extraction is almost syrupy in appearance and delivers a really smooth espresso. I was actually most impressed with the Macchiato that I made. 

Why is OBJ such a challenge? - good question. It's an "aged coffee" that is it's left in a warehouse to "mature" for a couple of years before being shipped. As a result we roast this quite dark without making it oily to kill off the "sacky" smell which I believe to be undesirable. Some part of this process clearly impacts on the ability of the water to get through the coffee though. Anybody have any suggestions?