Would you consider a Yamaha RX-396 Stereo receiver from 1999 "vintage"?
I think a lot depends on the design rather than age.
That Marantz is vintage and the design shows it. As I said in my PM yesterday, it is not a very well designed unit and by modern standards poor. The power amp section was frankly a mess. Distortion is 0.5% at power, and those old designs of solid sate amps actually increased as the volume went down! It is also discrete unit and could potentially be serviced, if you want to mess with that way over complicated design for no good purpose.
The Yamaha is constructed in a modern fashion, with many ICs including a logic chip. Components are surface mount. This unit would not be serviceable as I am sure the boards, and probably the ICs are NLA. The distortion of this unit is lower then the Marantz by a factor of more then 10. However the design of the Marantz looks as if it could have significant crossover distortion which many transistor designs of that vintage did. That means distortion rises as you turn down the volume!
Early solid state designs on the whole were not very good. This gave solid state gear a bad name at the outset, and gave rise to the "tubes are better" ideation which still is alive and well.
The first transistor amp that was any good and actually better than tubes was the Quad 303. This is not just my opinion, but widely recognized. Not only that it was very reliable. It took others are long time to catch up and produce solid state amps of that power class of comparable quality and many never did.
So vintage really should be applied to gear using older design techniques such as discrete transistors for instance. They should also be of superior quality like good aged wines. Junk old gear is junk and does not deserve the vintage acronym in my view.
