I retired as an dealer 8 years ago. My service tech of 25+ years still works with me on weekends with the goal of "keeping decent audio gear from ending up in the dumpster." We regularly "fix" old audio gear that has a high emotional attachment to their owner(s). We also provide performance upgrades by encorporating "newer thinking" into older (vintage) equipment.
I’ll just say that’s it’s suprising (sometimes STUNNING!!) how much additional music can come out of those old boxes.
I try to stay away from general statements, but will concur with others that at a given price point newer gear will sound better than vintage gear. But, if there’s something emotionally, or esthetically, appealing about vintage gear, there’s a 98% chance that there’s a path to an improvement in sonic performance. And many allow for a return to "factory stock" with minimal effort.