krikan, re "timbral difference"...
timbre..."The combination of qualities of a sound that distinguishes it from other sounds of the same pitch and volume."
Basically, the timbre of a speaker is it's sound signature. You want the signature of your speakers to match each other(timbre) so that you don't have any tonal differences from one to the other which can be quite noticeable esp on your front three speakers in a surround system where timbral matching is most important. With few exceptions, this is why you should generally stick with speakers from the same company. The M50s are "voiced" slightly differenly, as are the M3's from most of Axiom's speakers.
