It's been awhile since I drastically modified a vintage amp. I was challenged to mod is 1965 Fender Bassman AB165 to sound like a Hiwatt DR103 and Mesa MKI.
I started out by making the power amp, power supply, and Normal Channel as close to a MKI as I could. Although I add a few twists, the negative feedback loop is a bit more Hiwatt than Mesa.
Next was the DR103 preamp. Is it still Hiwatt without the Hiwatt lead dress? The cult of British amp enthusiast will tell you no. Wait, don't Hiwatt amps have more controls and inputs? My only concern was that it would be stable and not completely over power the MKI Normal Channel.
The end result was a very pleasing combination that I never would have thought to put together on my own. The MKI poweramp softens the blow of the DR103 preamp in a really pleasant way. This is now one of those amps. You just know from the sound of the first full rung out chord that there isn't and never will be another one like it. It's not just the circuit that I built. It's the history and age of it's container.