Distance from the front not the rear wall?

The Audio Physics method (Immediasound) has worked extremely well for me when I used it in smallish rooms. Having the chair within a foot or so, or even against the untreated rear wall was not a problem. It also allowed me to pull the speakers further into the room. I find the method works best with long wall placement of the speakers, which is my preference anyway. However, I suppose that's another bone to pick as most people I know prefer short wall placement.

I too prefer long wall placement.

The simple explanation is that

1) Bass response is always the worst close to a wall - just try it by walking around the room - you always get a more uneven bass response when you sit near a wall.
2) The secondary reflections will collapse the soundstage to the speakers - just try it by moving your position out into the room and you will find the soundstage grows in height and width and frees itself from the speakers. However, with the back of your head against a wall the sound collapses to the speakers.

Depending on your setup this will be more or less apparent. You need to have the speakers free from nearby reflections to begin with to hear 2.

The problem with Sonics explanation above is this statement:-

"Secondly, the reflections are shorter than the circumference of the head, so the brain cannot measure the time delay between the ears, and therefore cannot localize the source of sound. When the brain cannot localize reflections it ignores them."

This is obviously not true for a listener seated at 1 to 3 feet from the wall behind them, as suggested in the article). Physically the reflected sound has to travel at least two feet further than the direct sound when the listener is 1 foot from the wall. As the article mentions at the beginning, this is very bad because of the 5 msec rule which requires that NO reflections reach the ear prior to 5 msec.

If you apply the 5 Msec rule(which is scientifically proven) then you need a minimum 4 feet from the speakers to the side walls and at least 4 feet distance between you and the rear wall behind your head (as I recommended).

Why do I say 4 feet and not 5 feet (since 5 feet is about 5 msec)?

This is because the diagonal path that reflected sound follows will almost always be longer than the physical distance because the sound has to "reflect". You can, in some situations, get away with 3 feet.

The inconsistencies in the article by Joachim Gerhard should be self evident - although a lot of what he says about speaker placement is valid. Although, such a wide speaker separation tends to exaggerate the stereo effect often to the detriment of a more natural presentation in favor of a more impressive presentation.

IME, with speakers out from nearby walls (especially sidewalls) and absorbing room treatment behind the close wall to the listener, I enjoy better sound than from other arrangements.