It's a good call to find good CD/LP reference recordings. I wouldn't trust any but those made by the same company and preferably from a company that can be relied upon for good sound such as Audioquest. A good choice might be Mighty Sam McLain GIve It Up to Love, or something more acoustically based depending on your taste.
Once you've appropriate discs to compare then you can effectively follow Doug'sexcellent advice.
Once you've appropriate discs to compare then you can effectively follow Doug'sexcellent advice.