20 Year Old Amplifiers compared to 2017

I like a nice restored vintage component. I like working on them to a point. I've got issues with old gear though. 
First, folks ask WAY too much for it these days.
Second, condition and reliability are significant concerns. 
The third issue is repairs and restoration. 

Any 20 year old amp should at least be looked over and dialed in, if not completely recapped, especially if it's cap coupled. Getting that kind of work done is often not cheap. By the time you find a good example of something and put the money into getting it into good condition, has anything been saved? If somebody has a particular love affair with an amp then by all means restore and enjoy. If not, buy new. The field of amps has diversified in a variety of ways and I do think modern amps are better than older ones. 

The amp AB tests that I have read about...there is only a handful of them. They put people in unfamiliar rooms with unfamiliar gear and music...and of course it’s all too overwhelming to distinguish much. At audio shows you will sometimes hear people commenting that speakers start to sound the same. Anyway, we all have different hearing abilities. if someone can’t tell the difference between amps, it’s not accurate to assume that others can’t as well. 

I like to listen to a lot of different components in my system and can't underscore enough system synergy. That said, my biases lean heavily to the tube side of things and vinyl- keep that in mind when reading my comments. I recently ran an interesting test where I put up a new First Watt F6 vs a Bedini 25/25 that had been recapped.  Both 25 watt systems into 8 ohm doubling into 4 ohm. To my ears (and biases), the Bedini heartily outperformed the F6 being much warmer and relaxed.  To me the F6 was strident, thin and just to linear- a feature to one degree or another of all the solid-state gear I've listened to over the last 40 years. But there are listeners (one a good listening buddy who loves his Pass amps) who prefer that "sound" over a warmer tube sound which is great, as long as they are pleased with their outcome.  Btw- the last three years I've been listening to bi-amped systems in my primary rig- tubes on top and solid state on the bottom (vinyl, tube phono and tube line stage).  I can go into lots of detail on the tube amps I've rolled through but this thread specifically asked about solid state.  If the F6 represents a reasonable current state-of-the-art SS Amp and your biases lean towards a warmer sound, then at least one 40 year old SS amp can compete with today's high-end.  The Bedini amps, specifically the 10/10 and 25/25 to me, are really special and are the only solid-state amps I have been Happy listening to on a consistent basis. The 45/45 and 100/100 were good but in the end I let them go along with the F6.

i just purchased the new Rega Brio integrated and it sounds very good compared to my old Rowland Model 5 and Cohearance 2
good sound is now is comparable to amps of 30 years ago at a fraction of the price. what you get from the new Brio is sound that would cost you near 10K 30 years ago

The F6 is most definitely not typical of modern solid state amps. The transformer strongly contributes to the character of it's sound. The most "normal" of the First Watt line are the Aleph J and the F5. No transformers. No current sources. No positive feedback. Just very simple topology in single ended and push-pull. If you're looking for a tube-like sound you want a SIT 1 or SIT 2. The SITs are the only devices that resemble the gain characteristics of a triode. 
Personally I think the F5 is the pinnacle of technically proficient solid state sound in the FW line; some would say to a fault. Compared to the F6, the F5 actually has a useful damping factor, has half the noise, about 10% of the distortion, and about 10 times the bandwidth. It's greatest fault is it's unforgiving nature. The F7 is Nelson's attempt to tame the F5's brutality. I REALLY like my F5.