I have been browsing this forum for ages and there is simply too much information (kudos to you!).
I need to know the best possible opamp and tube upgrades and the process of installing them.
Also is anybody still making clear cases? Haha
I just left my case off.
Installing is easy.
I personally have enjoyed running WE 396A tube and Audio-gd SUN HDAM.
I think these are the most optimal top end upgrades for the D1.