Zeke can explain it clearly all he wants, as many other people have over the years. Jose modded does not mean it had a cascaded preamp. Jose modded could even mean a 330uf cap on V2A and or a line out that Jose put in there or his load box setup (even though no one knows when that cap showed up) and that appears to be the case. Mike Soldano also stated Ed had a Super Bass that he loved and it had a 25uf cap across V2A instead of a 330uf cap. The people closest to Jose all say it was a stock amp, Dave Friedman, Mark Cameron. Then there is Mike Soldano, John Suhr, Chris Merren and a myriad of others for over the years.
I have clearly explained the logic used why I feel the amp in question for VH1, 78, 79 tours were stock, stockish two gain stage plexi and superleads, the 1977 VH1 ROOM MIC cips of Jamie's Cryin, Eruption and early LIVE 78 tour clips clearly show what the amp sounded like BEFORE the studio processing, period end of story. Those who own or have heard a great plexi/superlead know that's what they are hearing all the characteristics are there. As good as any cascaded 3 gain stage amp sounds( think 2203) they sound and feel different to a variaced cranked two gain stage Plexi/Superlead, it just does. You can live in the land of denial for as long you like, there is a reason players gravitate to cranked a Plexi/Superlead over a 2203. You are clearly commited to your theories and that's fine. When you have a cascaded clip of an amp that has all of the correct characteristics of those VH1 mic and 78tour clips post them up. I have not heard one that sounds more correct than an actual plexi. The Metro amp EVH task force tried every cascade circuit known to man and most of them happily went back to a variaced plexi/superlead. If you don't want to use a variac and the whole setup then yes, a cascade is easlier to work with, get a damn good sound but it will not have all the characteristics that the plexi/superlead has. At a certain point close enough just has to work as even you will never replicate the VH1 recorded tone perfectly because that complete recipe is lost to time.
Oh BTW Chris Merren already explained what the most probable use of the second varaic was used for 20 years ago, it's interesting, is he correct? We will never know. Did I try it out with two vintage Ohmite variacs that I own15 years ago, I sure did... Was it interesting? Yes it was. Was it 100% conclusive? It was not. You can dig around o the Metro forum if you would like to read abou it.
Even if you build this magical Jose cascaded amp, without knowing exactly what was done in the studio for VH-1 the best you can hope for is the amp to sound similar to those VH1 Room mic and 78 tour clips.