Here's my homespun recipe as best I can describe it for best locating the Ohms based on my experience.
I find the sound overall is most balanced, focused and natural when the tweets are oriented so that two imaginary perpendicular lines projecting out from them cross just in front of your listening position.
Also, regarding best placement regarding soundstage and imaging, I go back to my observation in my Ohm f-5 review that the Walsh drivers act like sound projectors.
The imaging is best "focused" by placing these away from the rear and side walls so that reflected sound from each symmetrical location on these walls relative to the each speaker location arrives at your ears in the main listening location more or less at the same time, which is equivalent to saying that the overall distance the reflected sound travels is the same.
Regarding tonal balance, adjust the top end by orienting the tweeters accordingly and adjust the low end by moving the speaks closer or further away from the rear wall as needed.
Only much larger and more expensive speaks can match the overall lifelike presentation of the Ohms when set up properly, IMHO.