I sent this message to Mike at KCA also. I would like to get some opinions here as well. Please let me know what you think and how I may change this. "I am wondering what I should do. I have a new Z Prescription ES head. I love it but I would like to get more gain from it (earlier) without using an attenuator. What's happening is this: I recently bought a Creation Audio Labs MK 4.23 boost. When I use it with my Vox AC50, it boost but also slams the front end of the amp to give me a nice, smooth tube overdrive that I love. I also use it with my Soldano SLO and it does the same. That said, when I use it with my RxES, it doesn't give me the same outcome. It basically just increases the volume. That in itself is great but I would love to have it slam the front end of my RxES more and get that nice, natural, smooth overdrive. Is it a case of just swapping out the V1 in favor of a tube with more gain? Can you suggest something to me that may remedy the situation?"