ManualThe complete Handbook is still in draft status
First important thing: warm up Your system and chose a music track. It should be a familiar song and, according to my experience, it is easier with an acoustic track.
A good start is to put the horn at 16-17. As already said, it is an iterative process.
While the system is playing music You have to lift your ear up and down, even for several centimeters, moving the head up and down.
If the feeling of sonic coherence is in an higher position than the normal seating position (Picture 1) then You should move the horn 2mm to the front.
If the feeling of sonic coherence is in a lower position than the normal seating position (Picture 2) then You should move the horn 2mm to the back.
At the beginning it could be necessary to move the horn in the same direction for several steps, before reaching a correct positioning.
Target is to bring the coherence sensation at the sitting height (Picture 3). In this way the whole soundstage gains in energy, coherence and flow.
Next steps, in the final phase of the positioning, as soon as the best position is nearing the ear, then the movement of the horn should be reduced. In the end phase I normally move the horn of about 0,5mm until I find the most correct result (Picture 3)
The first times the whole process might need quite some time. Then, as soon as the experience increases, it becomes easier and faster.
Real needed it is only one time, at the installation of the loudspeakers, then it could be a good idea to check it at the end of the burn in phase. And, since the horn position is related to the room, then if there are some changes in the room (new or different couch, different distance from the loudspeakers) then it could be wise to check it again.