some 70's and 80's receivers seem to be popular

The brands mentioned above were/are very good.

I've owned Tandberg and Yamaha in recent years and both have delivered the sonic goods in my second, two channel A/V system.

The Advent 300 was another very good sounding though finicky piece.

If you do find a good-sounding vintage receiver, i.e Marantz 22xx series, if it is original and never been serviced, I highly recommend you take it to a good Tech and have them upgrade(replace) certain caps and give it a thorough cleaning and bench test. Most caps that are 20 years and older could possibly be leaking and/or on their way out. This will give you not only peace of mind but a better sounding receiver with many more years of happy listening.

The Nakamichi 730 was very good as was the Audio Pro 150.I had both. The Tandbergs would be the ones I would look for as they were more plentiful. Pioneer 1280 and 1980 ( I think there were the numbers) were very powerful and had a good amp section. Sansui made some good integrated amps in this period, as did Luxman

Just heard a Sansui 5000 on a pair of Vandersteen series 1,I think they were.Really good sound.....

The very early Yamahas (early/mid 70s) were excellent for their time. I don't know how they would stack up today, though.