@stereo5
This is nonsense. Speakers are not 'voiced' using a certain form of music, not if there is a competent designer involved! They may prefer a certain genre, but that won't influence the design for the reasons I presented earlier.
Inefficient speakers struggle because the have thermal compression associated with the voice coil of the drivers involved. It hurts them with any form of music so isn't rock specific.
There are specific measurements on speakers that can be tied to great sound for hard rock and metal genres, for example. I recall that this was all beaten to death in a different recent thread. If the designer doesn't ever listen to or care for such genres, his speakers wouldn't measure as such, i.e., would have been voiced differently., i.e., he would have pursued something else in the design space.