Hi JamieG and everyone,
It's no surprise to me that JaimeG's speakers sounded bright because of the tile floors and concrete walls of his room: the reflected high-frequency energy would be quite intense. But that's a product of the room, not the speakers!
Most speaker engineers--and that includes Ian Colquhoun, of Axiom--aim for a design that yields a balanced combination of bass, midrange and treble in a normally furnished room. The listening room at the National Research Council has a carpeted floor, bookcases and draperies along the shorter wall, with upholstered chairs and furniture. And the room at the Axiom plant is very similar. The M60ti's sound smooth and balanced in those rooms and will perform similarly in most people's furnished rooms--with no need of resistors installed on the tweeter to make the speaker less linear.
When you install resistors on the tweeter, you are changing the performance of the speaker. In effect, you are rolling off the upper octaves by a few decibels, altering the smooth response that's engineered into the speaker. It will be less articulate and detailed with the resistors installed.
So think about the room--the forgotten component--which you are using the speakers in and what you can do to it to make it more "typical" before you rush to change a speaker's carefully engineered response by tweaking it with resistors. For instance, I would not want to see resistors installed on the M22ti or the M2i. The response of both those models in a normal room is ideal, and will only be compromised by installing resistors.
A more productive approach would be to furnish the room with a normal combination of absorbent and reflective furnishings. Likewise, it isn't the duty of a speaker designer to adjust the performance of a speaker to compensate for badly engineered recordings--and there are plenty of those around. Just a few things to consider about music reproduction at home. . .
Regards,
