Have there been sound improvement in receivers over the last 30 years or has it trended toward the opposite?

With $250-300 in my pocket, I'm questioning whether to buy used vintage or second-hand modern. The primary application would be for 2 channel music listening, but a new model would add versatility.

Functionality aside, though a major consideration, would a lower-end modern Marantz such as the SR4001 equal the sound of a Marantz 2270 from the 70's? It would certainly offer a ot of useful features.
Thanks.