An easy way to improve any CD is to clean and improve reflectivity. I use a high-grade Groit best-of-show car wax, one drop is all you need, spread and buff, and you’re done. There is such an improvement you will not believe it. All you have heard is just shake their heads, dynamics, body, and tone all come forth. I’ve not played an uncleaned CD in many many years, I do try sometimes so I will clean a CD with soap and water to wash off the wax, play it and it sounds good, but nothing like it sounds before. No need to buy audiophile-overpriced liquids. $20.00 or so and you have enough for 100’s of CDs. I’ve taken some of mine to audio shows and played them and people say wow that sounds good, who mastered that I own it and I never heard it sound that good. CDs were turned on over the past several years, from being used as sources in the SOTA system to they sound like crap now. I guess all the reviewers had crap for ears back then. I am a vinyl guy and I have zero issues with CDs if mastered well like any source and cleaned with my wax.