Since you like Dream Theater, i am very sure you'd admire the drummer, Mike Portnoy.
That means, if you listen to classic metal, im sure you have heard of AC/DC, Slayer, Guns & Roses and Megadeth. I listen to songs from these rock bands you have mentioned above occasionally.
For me, I listen to J-Rock and J-metal. My most favourite form of metal is thrash metal.
You should listen to songs from Dir En Grey and Girugamesh, both rock/metal bands from Japan.
Most favourite Dir En Grey song~ [link]
Most favourite Girugamesh song~ [link]