@glennewdick @viethluu I think the question is pretty clear. I gave examples of exactly what I'd be comparing against on the old side. and my virtual system tells you I run a Luxman 509x today.
I've owned vintage Luxman gear from the early 80's specifically the L560 the predecessor to the current class A models. and I would put that amp up against any current amps. and it had 50wpc pure class A not the 30wpc the current one has.
I've restored 4 Sansui professional series amps, preamps and tuners all with surprisingly good results. the Sansui CA200 preamp was in my main system for a couple years while i looked for a preamp, had to spend big on a McIntosh C2700 tube preamp to supplant it. so yes, some vintage gear holds up quite well to modern stuff. just depends greatly on which vintage stuff you're talking about.
go ask a Altec, western electric speaker guy what they think. Or vintage Tannoy gold's many love them, maybe a Sansui Au111 integrated tube amp (that sell for over $5k now).