I am just guessing here, I did speak with Elliot a few weeks ago though. There is an updated volume control,which my 1 year old unit does not have. Elliot said the new one has fewer steps. He did not mention an increase in gain in the upgraded mk 3. In my system, I definitely have plenty of gain though. With my Jade and Messenger w/ phono, 9-10 O'clock is quite loud. I have never even ventured up to the 11 O' clock range. I am wondering now if the Messenger's w/ the tubed PS are in fact the Mk.1. Then, I would guess all Messenger's w/ SS PS would be Mk. 2's. I welcome any clarification here though. BTW, Elliot is a class act, and always a pleasure to speak with.