20 Year Old Amplifiers compared to 2017

Kosst,
My F5 at the moment is being worked on very capable DIY'er, who, based discussions he has had with Nelson Pass, is doing some the upgrades you describe above.  It difficult to imagine the F5 improving, but it is logical thatat it will do so with the improvements you describe.  
Finally, there are lots of facts and opinions stated in the realm of audio blogs, but yours I consistently find the most logical and informed.  Thanks for sharing your information.  Whitestix

I just was given a Denon AVR-2805 for Christmas. It replaced my entry level Yamaha RX350 from the mid-80s. The feature I appreciate the most: "Pure Direct mode was designed for those who want the ultimate in sonic quality by shutting down all unused circuitry for the cleanest and most precise stereo sound from any audio component in your system." and the AL24 Processor which makes even low-res MP3 files sound like 24 bit.

I always steered clear of anything but a 2-ch Stereo, and quite frankly, I doubt if I will ever utilize anything but 2 ch. Pure Direct Stereo. I have no desire to watch Blu-Ray videos with 7.1 surround, or have it perfectly equalize my 1975 circa Advents. But, to the question of whether older electronics sound as good as modern? I would say, vintage still rules the roost.

My 37-year-old amp and receiver have been serviced. Fairly inexpensive process. Hopefully will last another 30. And they're far prettier than today's amps/receivers. That said, I recently switched to a newer Class D amp because it has ARC, but I will occasionally use the old ones.

Oh, and while I'm making the case, double-blind listening tests are NOT scientific for the simple and very true reason that it takes at least days and more likely weeks or even months to get a handle on how an amp or other electronic component sounds

I have at least two problems with this idea.
1. A test that's good enough and scientific enough for every other field, including those involving life and death, is not good enough for audio?
2. If it really does take that long, then the differences would have to be so ridiculously minuscule as to be nonexistent or irrelevant.

Aardbear, I'm a CJ fan; I have a PV 10A and a PV 12L. The vintage CJ preamps are very special, which is why they have high asking prices. CJ claimed they had "The golden glow" back in the 90's, but since ARC got better press, they went neutral to compete.

There are considerable differences between ARC and CJ vintage; in regard to power amps, CJ is warm and mellow, while ARC is analytical, almost SS. A CJ pre and ARC amp works for me.

Reconditioned CJ is better (Better meaning a specific sound) than the new CJ's.

I have long wanted to upgrade my aged aragon28k preamp becos it doesnt hv balanced out and ht bypass.
2yrs ago, with a budget of usd12k, i went to many dealers and demoed against current highflyers, viz. Ayre kx5, accuphase, mbl， jeff roland, ml 326s. I found that either my aragon sounded better or same.
I finally bought a simaudio 740p without audition only based on reviews becos no stock.
Sold the 740p after 3months.
Guess what? My aragon 28k sounded far superior. Better soundstage, transients, transparent, speed, punchy and crisp.
So, sadly, after 25yrs, I’m still stuck with the aragon28k which is worth maybe just usd300 used.

I am now looking at T+A, Gryphon, ARC .... but i'm skeptical even the current usd$20k preamp would sound superior to the aragon28k