Increasing height of stand-mount -- what to expect

Hornguys, I am curious why the midtreble is the only area of concern when tilting or raising the height of a speaker. Can you please explain?

I might suggest first tilting them back to see it presents a better sound when roughly at the same height.

Then, if the mid-treble balance is better, any differences in height related to floor bounce can be heard by shimming the existing stands with a block or whatever.

Csmgolf, That is correct. Most people know the distance from the wall behind the speakers changes the tonal balance, however, there is rarely any thought given to the distance between the floor and the speaker which is a critical room boundary as well.

Usually speaker manuf design speakers such that the woofer distance from the floor is a specific amount. This relates to the woofer coupling to the floor for the intended bass response. Moving the speaker up chnages this distance & chnages the bass response. You might want to contact your speaker manuf to see if they have such a desired woofer-to-floor distance or not.
Yeah, sonics are not that good when your ear is above the tweeter since for most speakers the vertical dispersion is terrible (you can see this in almost every speaker tested by Stereophile). So, your idea to get your ears below the tweeter is a good one.
Usually the best sound is when your ear is 1" below the midrange driver in a 3-way & in between the drivers in a 2-way. So, it might actually be better for you to lower your seat.

I am not 100 percent sure on this, but I believe that any time you change the distance a speaker sits from a room boundry you are likely to change the tonal balance. The vast majority of the speakers I have owned sound different when moved only a couple of inches anywhere in the horizonal. I don't see how moving vertically would be any different. Note I said it sounded different and not necessarily better or worse. I like Rrog's idea of raking the speakers to get the tweeters pointed at your ears as a good place to start.

Instead of raising your speakers try tilting them back. You can use a level so you know they are equal or you can use a drafting T. Place the T across the back of the speak with the long end pointed toward the listening seat. Looking down the T tilt the speakers so they are aimed at ear level. You can also use a laser aimed down the T.

It depends on the speakers. Of course the general rule is to have your ears at the same height of the tweeters but with two particular speakers I have found this didn't work. My Silverline SR11s sounded much better with the tweeter raised a few inches above my ear. It was opposite with a pair of PMC DB1i speakers. The PMCs sounded best with the tweeter 4/5 inches lower. That was a bit of a shock.

Can you adjust the height of your listening seat? If you temporarily try an adjustable office chair, you could slide it around for the best integration of bass and also adjust the height for the smoothest, most balanced sound. I would try that first to see if you hear a difference. I have found it does, so much so that when my 6'-5" buddy comes over, he removes the cushion of my sofa before he sits to listen.

Can you adjust the height of your listening seat? If you temporarily try an
adjustable office chair, you could slide it around for the best integration of bass
and also adjust the height for the smoothest, most balanced sound. I would try
that first to see if you hear a difference. I have found it does, so much so that
when my 6'-5" buddy comes over, he removes the cushion of my sofa
before he sits to listen as the sweet spot is designed specifically for my ear
height.