I picked up an old Sony STR-AV880, not going to lie, mostly because it looked cool and '80s styled, plus the guy had the manual and remote and it was mint. I took out an old Sansui B-2101 amp and C-2101 preamp and put this Sony in its place. Can't tell the difference, acoustically. I'm not sure how much that helps since I just did vintage to vintage, but more meant to get at they used to care more about the features. That old Sony has MM/MC, all sorts of nice FM adjustments, tone controls, lots of things the new stuff doesn't care about. FWIW, the worst sounding "preamp" I ever heard was an old '90s HK receiver that the amp section was blown on, and I was using it as a preamp since it still worked. I hooked up an NAD monitor series preamp, and heard a stark difference between the two just from switching preamps alone with all tone control defeated. So it could be an HK thing.
Far be it from me to say vintage is better than modern, because I tend to heartily disagree. But the good old stuff is often still surprisingly good. The new Yamaha 2 channel receiver/integrated amps look quite nice, but those seem to hardly have much advantage over their older siblings other than just newer innards. The price differential can often make the older ones a better value, even factoring in some servicing. Then again, I never had good luck with vintage Yamaha stuff...it looks so nice, yet most the ones I have come across had issues.