Humm yeah that can be a tough one. Heres another thought. Most of the time systems that play perfectly flat for an rta (measurement device) sound like crap with real music. So should be music be reproduced exactly, even though you dont like the way it sounds? Of course hearing isn't linear either but if the sound is reproduced exactly how it was recorded then you ears should apply the same curve as if you heard the music live (assuming no change in the mixing) or am I mistaken? Just a thought.

I guess different kinds of music will emphasize different parts of the specturm and because different speakers will also emphasize different parts it stands to reason that when you put the two together some will sound better with certain types of music. It takes a lot of time and effort to get a system that sounds good on a variety of music.

You also have to take into account the install is a huge factor in how the speakers sound. Some may be designed to work one way and another manufacturer may design to work in a different environment/placement. The two different speakers may need different placements to get the most out of them. I apologize if this has gotten a bit off topic. Again these are just my thoughts.