When were the best tube amps made?

The best amps were made when Japanese thoroughness joined American ingenuity: think Wavac, Shindo, Yamamoto, Kondo and nowadays Allnic, Zanden and Luxman

and an honorable mention to the OTL crowd: Futterman, Graaf, Ralph Carsten and Dave Berning

In terms of engineering brilliance and sheer transparency, timbre and attack Nobu Shishido’s Wavac designs are unequalled in my mind 

@atmasphere,

not sure whether Zero Autoformers are really zero cost. I used them on a Graaf GM20 about 15 years ago and while bass was significantly tightened, the overall SQ lost pizzazz. It felt a bit like a Ferrari on Qualudes…