This is one of my little project as SUPER HEADROOM FAN at least one year ago.
Before upgrade, stock '04 Premium Module.
Then I upgraded it to '05 Max module level by myself. The only thing I can change at any time but not change is the 2134s. I still haven't upgrade them to OPA627 yet as I think it is not cost effective to me any way and my MOH's sounding is damn good already(Couple months later after I did this upgrade, I got chance to compared it "side by side" with stock '05 MAX module, I trust my ears.
Side Note: This is not the picture of the final module board, I did not even clean up the module board yet. I am lazy, I don't want to open up my MOH again.
To me this upgrade is for fun. Some challenges at implementation stage are soldering temperature control when dealing with tiny caps, also developed my own procedure for desoldering whole module board off from the main AMP board(Trade secret