"They simply don't make them like this anymore"

I am confused. Do you mean to say that these vintage pieces are left behind, or that they can compete with modern designs?

"Back in the day" we referred to Phase linear as "Flame Linear." Not only did it sound like crap but it it went up in smoke on a regular basis. Lots of power for low $$ when it worked, unfortunately it didn't work all that often. At that time, Carver was "brilliant" in marketing unconventional designs that turned out to be either unreliable or sounding like crap or both. Maybe he's gotten better since then.

While Jadis is certainly still current, they were more popular in this country during the era that you mentioned Threshold and Carver in.

I had one in mothballs, and recently sold it to clear out some stuff. I have two other pairs of tube amps that are held in the highest esteem, and after I burned in the new tubes this little Jadis was providing me with the best sound I have ever had in my systems. You can imagine I was not happy to see it go, as I have yet to hear a better amp.

Years ago we had the Shelby Mustang, GTO, AMC Gremlin and the Pinto. In audio we had the Marantz 8B, Fuzz Linear, the original QUADS and the Blose 901. Sometimes it's a classic and sometimes it's a piece of crap. The trick is in knowing the difference. Often this is easy, as in the case of the Marantz 10B tuner, which currently sells for 4-5 times it's original price of $599. That's a good clue.

The thing is: the output transistors that are available now are much more linear and faster than those of past years, not to mention the superior capacitors of all types that you can get now. Some of these end up inside newer amps. Same designs, better parts.

To me the value in vintage quality gear is in knowing the items to seek, understand they will most likely require service due to their age, and avoid spending really big bucks on comparable new products.

A Threshold SA3 or Krell KSA50 or vintage Kondo tube amp is a great piece. They are especially attractive when compared to the new prices. A used Ongaku can cost around 20k; servicing/upgrades will add around 5000 to that cost. A new similar product from Kondo San starts at 40 large. That is the motivation; same thing applies for something like a Levinson 27.5 vs a new/used current model Levinson.

With the rare exception of collectors it is the price that matters. When the older pieces are serviced/upgraded they are very close to most comparable modern replacement units.

Stick good Bilsteins and quality wheels/tires/sway bars on a 1970 Chevelle SS350 and it will handle right up there with a modern similar sized car. Same principle.