Many manufacturers have recommended discs that they and their customers to listen to regularly or use for testing. Go to the manufacturers and give it a try..
Any sites that recommend must have music?
I know that most of us are into this hobby for the enjoyment of music. It's great to find a great new piece of music regardless of if it's old or new. Are there web sites that have lists of recommended music old and new by catagory? I understand that lists like this can be subjective but at least maybe a good starting point.