For what it's worth, I think the response to mbhaub is disproportionate, and engages in some reverse-generalization. The story, for example, goes that Pierre Boulez' second piano sonata brought Yvonne Loriod, an accomplished performer of the modern repertoire, to tears.* I could be wrong, but I doubt that most popular music of the age brings its performers to tears. It would, however, be unproductive to let this devolve into a classical vs. metal flame-war.
To both answer the OP's question and give metal its due, I would say that thematically, musically, and emotionally, metal has some things in common with echt-Romantic material. For example, Wagner's Der fliegende Holländer has parts that would remind metal aficionados of various genres in turns. Thematically, both Holländer and Die Freischütz, though not exactly high Romanticism, would put people in mind of themes and ideas in some metal. There are plenty more examples of such consonance.
Once you have the theory, the instrumental chops, and some affinity for the the central Germanic repertoire, you could move from classical to metal easily. There are enough thematic and theoretical overlaps to make it an easier transition from, say, a chamber ensemble known for Franz Schubert to any of the major metal genres. Still, to get my digs in, I might also say that classical has some other things going for it that metal won't in my lifetime get, like first-rate composers and musicians devoting their lives to saying something new with "old" instruments and styles. Even Boulez scored for traditional instruments, in addition to his innovations.
*See Hopkins, G.W. The Musical Times. Vol. 112, No. 1540 (Jun., 1971): 560-561.
