20 Year Old Amplifiers compared to 2017

20 year amps most are ancient history unless you are very nostalgic.Good luck though.  

I have mixed feelings on the subject, but in general, I feel there are not many changes or real improvements.  We do have Class D now and it has developed into a viable audiophile amplifier. I own an amp that I built with Abletec modules, it is quite good.  Class A or A/B .... What has improved is the linearity of parts,  better outputs, lower ESR caps,  these have offered us better sounding amplifiers.  
So what I am saying is the thing that would make a real difference is circuit design.  I can see someone coming along with a killer design and creating a incredible amplifier today, but in general,  solid state amps are indeed very similar for the past 30+ years.  
I had an old Sumo Nine that my old mentor Ed Martin from Marcof modded.  He went overboard with the replacing mediocre parts with best parts available plus increased the filter capacitance 3 times.  A few years ago this amp took a lightening strike and I lost it, but he has it and is working on using different outputs, but that amp would really sing,  I compared to many amps and kept going back to it.  On the other hand,  I've heard some designs modified and it doesn't matter how many parts upgrades you do,  the amp just didn't respond... So, a good design is where its at.  I think that there are alot of old amps that could be improved to compete with the best today. I also believe that with the improvements in parts designs that there are plenty of great things still coming. 

Thanks for this thread -- it's raising all kinds of points that make me realize how much I have to learn!  willemj started his post with a statement that I don't understand:
"Amplifier technology reached maturity in the seventies, when output transformers were abandoned in solid state amps. Ever since, well designed amplifiers used within their specifications have exceeded human hearing acuity. "

Could someone point me to a source that would help me understand this?  I thought all power amps, even Krells, use power transformers, so he must be saying that less sophisticated amps have two transformers, one of which is on the output stage.  Assuming this is correct, what is the difference in their function, and why is it bad for SS amps to have transformers on the output stage?

Sorry I'm such a newbie, but we all have to start somewhere.

Some may disagree, however I believe MID-FI gear really took a hit in the late 70's until the 90's. Much of it build wise. Pioneer had those gross tan, plastic faceplates. Technics had cheap looking "graphs" printed on the faceplate, AKAI tape deck LED meter strips only had 5 lights per channel, just junk everywhere

Amplifier technology reached maturity in the seventies, when output transformers were abandoned in solid state amps. Ever since, well designed amplifiers used within their specifications have exceeded human hearing acuity.

@cheeg, As I pointed out earlier, the statement you quoted isn't correct on several counts. I did not address the output transformer bit, but other than MacIntosh, that really wasn't a thing with solid state amps even in the 1960s. It may be that what he really meant to say was 'coupling' or 'driver' transformer, as a good number of older designs from the 60s and early 70s did employ audio transformers to drive the bases of the output transistors in the design.

As far as 'their specifications have exceeded human hearing acuity', this statement isn't true either for the reasons I stated earlier in this thread.