If you are going to use metallica...the black album is good but you should also try the Berkeley album with the orchestra. My old favorite is, "I like the cars that go boom". Plenty of bass and tweets.
Of course I always pop in the art of noise for stereo panning effects.
For guitars and sound purity try "The Sundays" or good old Rod Steward's unpluged.
Good sh..t!!!!!
