In the world of old cars a Vintage is pre-1930 and a Classic is generally thought to be from after the 1940's and older than 25 years.

Some cars are obvious Classics, but others qualify that no-one would ever have thought to have any merit as a collector's car - any offers for a concours condition Morris Ital, anyone?
No, I thought not!!

THEORY A:
Classic hi-fi is defined by what was current (or cool but unaffordable) in the youth of whichever drooling casualty is defining it. Or it's the stuff that was around when they first got interested in hi-fi (not necessarily the same thing).

DISCUSS

THEORY B:
Ebay has turned the whole thing on it's head

DISCUSS

THEORY C:
True classic or vintage items must have some degree of 'merit' in addition to age.

DISCUSS