Not sure about this, but I think if a speaker could do symphonic music right, it will get heavy metal right, you really have to do an awful lot well in a speaker to get symphonic music right, including scale and dynamics. There are certainly speakers that are great for solo acoustic singer type music that can't quite get symphonic music right since so much more is demanded to reproduce a real symphonic presence. If you can do Mahler, I think you can do Metallica IMHO.
Just an observation, I think you can really screw up a great speaker when you try to make it produce real bass below 35hz or so, that insistence on the lowest bass really challenge a speaker, an amp, and a room. A long time ago I decide I was willing to give up that bottom octave to have a speaker that was "the best" for me. But then again, I don't listen to alot of symphonic or heavy metal:)
Just an observation, I think you can really screw up a great speaker when you try to make it produce real bass below 35hz or so, that insistence on the lowest bass really challenge a speaker, an amp, and a room. A long time ago I decide I was willing to give up that bottom octave to have a speaker that was "the best" for me. But then again, I don't listen to alot of symphonic or heavy metal:)