I Just wanted to share an experience that surprised me in my search for the right tone recently:
I have a '76 MK2 Super Lead that I recently took in for some work; mainly to have it returned to a stock configuration and have a 'cap job', rebias and new tubes. The amp had a Master Volume mod which I had removed as well too. The idea is to run the Marshall with a hot plate directly into one of my 4x12's - I first heard about using a hot plate from James explaining his setup here - thanks! I liked my Marshall with the Master Volume mod, but something wasn't quite right. The distortion was very 'tight' with lots of clear little jagged peaks for teeth, but I wanted to hear more space between the peaks and the peaks themselves to be softer.
The sound that's always stuck in my mind has been a combination between Uli's solo on 'Top Of The Bill' & that first chord James hits after his solo on 'The Hunted Heritic'; somewhere between these two sounds is where I wanted to be.
So while my Marshall is in the shop, I decided to run my little 40 watt tube (6L6 duet) Pignose with the hot plate into the 4x12. I had never heard the Pignose wide open, but what a surprise! The amp has great power tube distortion and with the hot plate's bass boost on it sounds nice & thick with a smooth breakup. Even with only 40 watts, the amp has plenty of muscle and brings me closer than ever to having a great tone!
I guess my point here is that it didn't take a kilobuck amp to get a great sound as much as it was being able to let the tube circuitry come into it's own through the use of a hot plate :)