People who negate the validity of modern classical music are shutting themselves off to a world of deeply impactful and often strange music.

The late Johannsson's Drone Mass is a wonderful example of this world. It starts off so slow and sounds genuinely ancient (it is obvious that Johannsson studied the conventions of mass and Egyptian funerary chants to give the listener a sense of authenticity). It's quite shocking when about a third of the way into the album low and abrasive electronics change the sound of the music entirely, creating the drone element of the drone mass.

Overall a somewhat intimidating experience, but worth a listen no matter your level of friendliness with modern classical, and best enjoyed in a moment of calm and quiet.