I only want to spend that kind or resources on absolute favorite records. I am filling in the rock and roll and R&B portion of my record and CD collection of artists ranging from the Beatles up through the Sex Pistols. Are there any other well known albums like "Let It Bleed" or "Layla" I should avoid, or might already have, that will need to be purchased or bought again in upgraded formats.
... there is a lot to sort out and understand about why any recordings sounds the way it does in any given setting, or because of what went into it while recorded or remastered. It's been interesting to learn about that here and other places from those more intimately involved or knowledgeable about the recording process, and those who know the ins and outs of various pressings and mediums.
Okay so here's the deal. There's some really bad offenders in the recording quality area like the Rolling Stones, but even they managed to get a few things right here and there, or so at least I am told. Springsteen is another major offender in the Hall of Fame for Great Music Recorded Badly.
But mostly this is one to take on a case by case basis. A better approach if you really care about recording quality is to start paying attention to the recording and mastering engineers. If you see Doug Sax The Mastering Lab you know its gonna sound good no matter if its Styx Equinox or Linda Ronstadt and Nelson Riddle.
Its a shame you seem only interested in CD because the only foolproof means I know of obtaining ultra high sound quality is to buy from Better-Records.com which although insanely expensive are also insanely good sound quality. Which has so much good solid info on recordings and sound quality its worth a visit even if you only buy CD.