Another soundstage question

IME soundstage height is enhanced with equipment which has good HF resolution  (the low level detail needed is often lost is lesser equipment) but a lot of speakers don't really open up, soundstage wise, at lower volume. I had this experience with both Quad 63's as well as some box speakers with lower sensitivity driven with tubes and SS. At higher volume they became absolutely holographic.

When you are working with set up don't forget to consider ceiling reflections can be as important as side wall reflections, as can proper toe in and listening chair placement. FWIW  I doubt that you will be able to get the height effect just by tilting or lifting your speakers although you can certainly change to tonal response to some degree (not necessarily always a better effect).

Have fun, and take your time.

Kalali, I just re-read your OP. If there is anything that really sticks out re speaker set up that I think might influence the height issue for you, is the distance your speakers are from the wall/bay behind them. I really don't know your rooms dimensions but if possible I'd start with the speakers about 5ft from the wall behind them and adjusting your listening position accordingly, maintaining the equilateral triangle, toe in according to ear, and see what happens. To get the feeling of height (if this information is on the disc, which more than often it is not) is IMO the  holy grail  of audio. I used a test LP/CD called 'Depth of Image' by Opus3 which is just outstanding for obtaining the best soundstage possible. I spent years chasing this effect (and lots of money foolishly)!

Kalali, FWIW, and it has already been touched upon, often much of what folks are willing to accept as 'height' is a result of the design of the speakers which might have no relationship to reproducing what is actually on the disc. For example, planar speakers can create a very full sound stage in all dimensions including height, but unfortunately often what you are hearing has very little to do with accurate reproduction of the size/tone of the instrument/voice etc which is being played.

 Just listen to a solo voice which on panel speakers can occupy the whole stage (perhaps what is were the term 'big mouth' is most appropriate). On these speakers, to compensate for this manufacturers add a ribbon tweeter to bring the high frequencies into better focus.

Then there are omni directional speakers which by design rely on reflective sound to create a large multi dimensional sound stage. They do work well with big orchestral pieces in making them sound like a live performance, both of which have reduced resolution and specificity (unless you sit in the orchestra pit regularly). 

Then there are 'box speakers' which can, if properly designed, set up, driven, etc, accurately portray the music as recorded, if that is what is important to you. Unfortunately a lot of recordings really have no 'height' element in the pits/grooves. The effort is great and the rewards can be small. 

I think that is why so many folks love omni, panel, and electrical speakers. With a few notable exceptions, the sense of a full sound stage is always present and rarely faithful to the recording.

In setting up box speakers to get maximum soundstage reproduction I think you are best served by minimizing the effects of reflective surfaces and the effects of too much bass or treble response (too much bass masks high frequency information, too much upper mid range/HF information gives bright unnatural sound not heard in real life. (Unfortunately many folks think this upper frequency information is evidence of 'resolution' capabilities of their systems, a thought encouraged by a lot of manufacturers/retailers, etc)

I've overstayed my welcome by now. Find a copy of Depth of Image! :-)