20 Year Old Amplifiers compared to 2017

Thank you for the response, i was not aware that the cases were no longer available with upgrades.

Mike has a lot of Takachi cases left over because of folks upgrading their original orders in his first three or four lots. Most people decided to upgrade from the Takachi case and wait for him to finish production of his own beefier upgraded cases. He isn't offering the Takachi case anymore because he can't get enough AS1200 modules from B&O to meet immediate demand and he wants to focus on his own in-house brand offerings/cases. Don't know if he'll ever decide to offer the kit again. 

@photon46 - I was reading another forum today and there was a reference to this old article on Tom’s H/W re: a blind audio test they performed. Its a perspective from outside the audio world although the conclusions are not as dramatic as the Stradivarius test you mention.

http://http//www.tomshardware.com/reviews/high-end-pc-audio,3733.html

Parts are parts and they are greatly better now than 20 years ago, but I don't think well known makers have adopted newer circuit designs; they are all lights and copper. But grounding, controlling vibrations,ac purity and rooms are more important.
I used to be a tuby with tubes only used having bought 2 ARC Dual 75s, a SP-3 preamp,, and Infinity Servostatic in 1973 and thinking nothing could be better. Now I have more invested in ICs, PCs, speaker wires, grounding, and ac supply than components. I just wish that I could have had this and enjoyed it since 1975.

Strongarm

I just sold my late 80’s era ARC D70Mk2. Replaced it with a pair of new Mono blocks that use the new KT150 tubes. The ARC was an awesome amp...even by today’s standards...back in the day...NOTHING could have touched it! However, the new amps are so much more resolving and a lot more capable at both frequency extremes. The new tubes may be accounting for this, but the fact is that the ARC was still highly competeive in my system after all these years...VERY impressive.
Have we seen an increase in SQ from the latest amps compared to yesteryear...I vote yes, but not to the extent that one would expect over this period of time.