The DRD is explained here:

http://www.stereophile.com/content/unofficial-dynamic-range-database

Dynamic range is the difference between peak and quiet moments in a soundtrack. Low dynamic range makes recordings sound compressed and "Loud" ie. modern pop music. sick High dynamic range makes recordings sound big, expansive and "Live" or realistic.

Here is a great recording with awesome dynamic range that gives you the "OMG, He's right fucking here!" sound. cool This is definitely a re-master worth getting if you like blues.

http://www.amazon.com/Folk-Singer-Muddy-...ers+folk+singer