I recently had a vintage solid-state receiver cleaned up and an IEC inlet installed to allow me to use a high-end power cord. The results were a huge improvement in resolution and a decent improvement in transparency. The noise floor also dropped due to the improvement in resolution. I've also replaced the captive zip-cord power cords of a Sony ES CD player and ES tuner (1990s vintage) with high-end power cords with even better results. Both pieces are in my main system with the CD player used only as a transport. Granted, the power cords cost more than the components themselves, but these, too, are available as high-value items on the used market. Even a $300 power cord will give you a lot of sound quality over cheap captive power cords.
Did the Old Receivers Sound Good?
Before the high end started, we had all these receivers and integrated amps from Pioneer, Kenwood, Sansui, Sherwood, etc., all with incredible specs. Then somehow we decided that specs didn't matter and we started moving to the more esoteric stuff from Ampzilla, Krell and whoever, but the specs were not as good. My question is - Did the old Japanese stuff with the great specs sound better? I don't remember. I'm asking because many seem to be moving back to the "specs are everything" mindset and I was thinking about all that old stuff with so many zeros to the right of the decimal point.