I was taking exception to your having suggested that "Everything in prog metal owes itself to the innovations created by jazz and classical music. Without question.". This is wrong. The backbeat played on the drums is one example. The use of effects (and how those effects influence both the performance, and timbral aspects, of the music) is another.
Actually, I would disagree...although I was referring to more then just the use of drums or guitar effects...that's the carrot and peas, but the steak is everything else. Perhaps I should have said "almost everything in prog rock came from classical"....and if you look at the original prog rock bands (Crimson, Yes, ELP, etc..) one of the first things they did was throw out the blues, and substitute western classical influences..and if not for those 70's pioneering bands, your prog metal would not exist either...metal would have likely stayed in the purely hard, blues' based sound...like AC/DC. It's entirely possible, you know?
As far as the timbral aspects...there are still a lot of similarities...use of a chorus box? Classical musicians just double parts and get a natural chorus effect.
Distortion? Have you ever realized how "distorted" bowed instruments can sound? There is almost a natural distortion and the use of the bow gives sustain naturally.
And as far as the sense of "doom" and "heaviness" prevalent in modern metal...look no further then wagner.
There is classical music out there so frightening and heavy it makes a lot of metal music seem like camp fire songs in comparison...only the music is not artificially heavy as is a lot of metal. In metal, I think they try too hard to be bad-ass.
But listen to "the scythian suite" sometime if you want to be frightened. Then move on to Xenaxis, Lygeti and Elliott Carter...if you truly want to be frightened. And I should warn you, it wont have any of those "cookie monster meets UFC" vocals needed by metal to imply scariness.
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