And I liked the music of previous secret level, don't remember the name now, though. It sounds so evil, and dark.
Same tune as from the final level of Wolfenstein 3D - Spear of Destiny, btw., where you meet the Angel of Death who holds the Spear.
Also the music from the level 29 (darn, again forgot the name, something with Spirit, need to play Doom 2 again, I guess..) is pretty good.