Dynamic Range of Compact Discs

I've been building my system and enjoying listening for years and every now and then I stumble onto something that makes a real difference. This may be pretty basic stuff and I feel embarrassed that I didn't know it, but I didn't realize I could have a copy of a CD that sounded horrible and then find the same CD with a different release date that sounds divine! I've been a CD bin diver at Walmart and I am finding out that most...not all...but most of those CDs are crap. Especially the greatest hits CDs. I've recently been reading about the loudness wars of the '90's and the effect they had on recordings. I stumbled on this website that lists albums and the different dynamic ranges of the various releases of that album..dr.loudness-war.info. This has been a game changer. I have a copy of the Dark Side of the Moon that I bought when it first came out in the early '80's and I have a copy that was remastered and included a SACD layer. I don't have a SACD player but I thought the remastered version would be better and I've been listening to that CD for years. After referencing the website I found that the original I bought has much better dynamic range than the newer one. After years of never listening to it, I popped it in and it DOES sound better. No doubt about it. I never noticed the difference before because I never listened to them both on a good system. I also had purchased Mothership which is a Led Zeppelin greatest hits collection and it has poor dynamic range. I have now purchased each studio album while paying attention to the release I was buying and I am enjoying Led Zeppelin as never before. My Pink Floyd collection other than DOSM was good already. It pays to keep reading. You never know what you might learn!!