Ok, I own a 1978 Marshall JMP 2204, 50 watt master volume. I wanted a gain increase mod so I took my amp in and I was recommended the "Lee Jackson mod". I waited a while and I stopped in every now and then to ask about the progress and I waited a month to get my amp back. I was told the tech was changing the tubes from stock to el34s and 12AX7s and adding new caps and a few other things I cant remember. Now that I got the amp back home, I fired it up and....it sounds the same. I was thinking I got jipped, so I took the back off....yep, there was certainly new tubes. But I dont hear any gain increase. The guy I went through said I would still need boost pedals (EQ and overdrive) to get the sound I want, so whats the point of the mod? Does anybody know what this Lee Jackson mod is in detail? And why do I hear no difference at all other than a slight marshall growl? I even put the preamp up at 8 and sometimes 10 and thats it, slight little growl. I asked the guy if they did the one wire mod and he looked at me like I had 6 heads. He said he had never heard of it. Any takes on this?