It's a plate-driven tone stack, no cathode follower. I can't imagine needing a Hot Mod, I found it having plenty of gain, and I didn't use the rhythm clip. I love the 2525H, just have to dial in those Masters and boost it!
I searched for it and found the page but didn't know if that was a reputable source, etc. I knew about the mods but seemed like a lot of the information was really old do didn't know if they were even making them anymore.