I think that maybe you can’t polish a turd, but perhaps you can get rid of the smell, LOL! Growing up in the ‘70’s, I have listened to most of the classic rock from that period hundreds of times, such as Led Zep and Jerthro Tull. Having heard the commercial release so many times, I have been drawn to bootlegs from that era, sometimes concerts that I actually attended. I have found that with a good, well-balanced system, like I have I think, even the bootlegs that are not great sound better on my system because of the way that the soundstage is presented, with depth and width, so even if the SQ can’t be improved, the listening experience can be. I am very pleased with the way my system presents everything, good or bad. Good quality recordings sound amazing and bad quality recordings sound less bad.