Perhaps in a drag-race or simple oval, with drag-race being watts into 8 ohms, and simple oval, being THD on a sine wave, then I would agree with you. Put them on a road course (real music), and that "old" Camaro or Corvette is hopelessly outclassed no matter the engine upgrade or what tires you put on it. Only way it competes is with effectively a new chassis under the old body (and even then it needs aerodynamics upgrades), so really it is not an "old" Camaro or Corvette any more is it?
Like a old Camaro or corvette, etc... being refitted to take on a modern
carbon fiber bodied racing F1 Ferrari, on the track.... and be dead
even and..in some minds... even win. Imagine that.
The idea of the new circuit and so on being better, exists as companies have to sell you the new in order to be alive and exist, so expect them to convince you that all is new all the time --- when in fact it is not. Not at all.
While there is truth to this, these receivers are from a period where IM distortion was poorly understood, hence why later products like the NAD3020 or even the Sansui integrated mentioned above are better.
(link is for the image of a ’properly’ modded out NAD3120, which, when
finalized [finally finished], might [and generally will] exceed the
sonic qualities that most seek to experience from a modern $5k
integrated.)
https://www.canuckaudiomart.com/forum/viewtopic.php?f=22&t=45215&p=708943&hilit=nad+3120...
A single set out 3055/2955 output transistor places some inherent limitations w.r.t. what loading this will work best on. Those same parts are still available, likely better quality or at least more consistent due to modern process controls.
Those over-priced "audio" electrolytic power supply capacitors are certainly great marketing by the likes of Nichicon and others. Literally sell themselves, as some people are convinced they are "better", and it becomes a self sustaining market, no actual specifications needed, just some words on a marketing sheet. But better than what is the question? Better than a 10,000 hour, 105C, modern capacitor with high ripple current and low ESR (and lower cost)? .... Weird that some of these high end audio capacitors have audio specs similar to a few generation back power supply caps (but with poorer rated life).