"i always thought that vintage receivers play best with speakers of the same era..."
Interesting observation but not my experience. I suspect its a more psychological effect mixed with nostalgia. My vintage JBL L40 speakers sound so much better with my current Vincent SP-331/tube preamp combo when compared to the Pioneer SX-980 that I used (and I still own) when I bought them back in 1977. Of course they are all now boxed up and live in the basement.