I have heard most of the recommendations on here and agree they are all excellent recordings. Thought I would add one that most people probably wouldn't think of, or ever hear. It is Deborah Allen-Delta Dreamland. Overall it is an outstanding recording, but the part that I like and use is, at the very beginning of the title track, it begins with crickets chirping, it then blends/begins with the unique sound of a steel guitar. This is where you can actually use it to discern subtle differences in interconnects, wire, or anything else where you really need a high dose of something to audibly hear differences. If your system has any "graininess" or any other problems you may be trying to tame this is a disc you can use, or use it while evaluating a system to see how "real" it can sound. You should be able to get this for cheap as it has not reached "Audiphool Status".
