What is the best HEAVY METAL speaker?

Something that has a smooth, grain free top end and a warm midbass...vintage Infinity...also Klipsch have that boogie factor if one can deal with a more forward sound.

Altec a4

I'd stay away from horn, electrostats and planners.

IMHO, metal needs critically-damped, very articulate dynamic (cone) speakers driven by solid-state that can really control the speakers. You can lessen the requirements of the amp if you high-pass the speakers and use a set of servo-subs.

A good track to test a "metal-worthy" system is Tool's "The Grudge". Listen to the accelerating kick drums. Each impact should be well defined (and not a muddy mess). Vocals should sound distinctly layered on top of the sonic fury. The engineering / production isn't perfect, but if you can get this song to sound "right" you're moving in the right direction.

Wow thanks for the suggestions, there is a lot of good advice in this posting. My budget is 3000$ and I have already tried the Klipsch rf7, Energy Veritas 2.4i, and grew up with JBLs on a Phase Linear system. Picked up some JBL Studio 530 bookshelf speakers for a seperate system and I am really impressed with horn tweeter in this series of speakers. Really be interested in hearing what the 590 towers would sound like, I know they would be better than the Klipsh. Find myself curious with Dali Evendence 870 with the soft tweeter design and two 8" woofers also. Someone here in Seattle has some for sale for less than a thousand bucks. What about NHT? 3.3 maybe?

Not sure about your budget and room size but for double drum bass and heavy metal guitar riffs you cannot go wrong with the GoldenEar Triton Two tower speakers provided the room is big enough to handle the bass.