I had a Joule LA 150 mk II in my system for a summer while awaiting repair of my main system line stage. I seem to remember that there were jumpers inside the cabinet that could change the output impedance of the line stage, but without an owner's manual or some direction from an owner, I wouldn't try to advise you. I gather the company is no longer- there is one web page that collects some info on Joule equipment but I didn't see anything about this in the quick perusal I did. I'm confident an owner with a manual can help you.
