How Much Are You Missing From 20khz to 45khz?

The less phase shift, the better the imaging.

Tonality will also improve since phase shift causes improper summing of harmonics. I'm not sure about speakers but amplifier has at least 45 degree phase shift at -3dB frequency limit. My -3dB@60kHz amplifier has 20 degree phase shift at 20kHz. Newest amplifiers from Jeff Rowland have 350kHz bandwidth.

Bifwynne, no speaker has anything like what I would call a linear curve. If the bumps aren't too bad often that's pretty good :)

Hi Mitch4T:
I recently upgraded to some of the new Reference 3A Episodes, which have a "supertweeter" that covers from 20khz to the upper 40khz area. After some experimenting with blocking off the supertweeter, I have noticed that it does certainly add some positive effects to my music, but not on all of the recordings I listen to. What they add does not seem to be anything that is part of the texture of the music itself, but to the ambience of the soundstage being created in my room. Some may call this "air" to the soundstage. It is a subtle improvement at best, but it does make a difference. It seems that some of this upper frequency information is deleted or missing in about half of my CD collection.