I listened to:

Virtuosity...technical prowess...experimentation...These are the best words I can devise to describe this fairly niche sub-genre.  Neo-Classical Metal (wikipedia, allmusic) is almost exclusively instrumental, and seems devoted to exploring the technical musical possibilities of the instrumentation commonly used by Metal musicians.  As the Wikipedia article points out, while not "neo-classical" in the strict sense as used by Classical music aficionados, this music does look to Classical music (particularly Baroque music) for inspiration.  While some artists, notably the Great Kat, are known for reinterpreting canonical Classical compositions in a Heavy Metal style, others appropriate the Classical tradition more loosely, playing with things like counterpoint and atonality.  To be honest, I don't love this subgenre.  Don't get me wrong; the musicianship here is absolutely top-notch.  I guess the blending of genres is just too much for me.