After some offline discussions with mijostyn about the difficulties in taking accurate measurements of dipolar speakers such a the Soundlabs that he has and the Apogees that I have, as well as any other dipolar speaker for that matter, I found that his experience and advice in this area proved to be correct and very helpful.
>> YOU MUST BLOCK THE REAR WAVE OF A DIPOLE SPEAKER FROM REFLECTING FROM THE WALL BEHIND IT IN BOTH STEP 1 AND STEP 2. <<. Otherwise, you will get comb filtering which produces all sorts of undesirable side effects. Even though your graphic results may not show what appears to a traditional repeating comb "tooth" pattern over a wide frequency band, you will probably immediately notice a problem in step 2 when the driver distances appear. Your first clue is when you see unrealistic relative distances between the drivers in your main speakers. I have found that these driver distances should be within the hundredths-of-a-meter without manual adjustment. I’ve also found that manual adjustment won’t fix this problem either. If you take these unrealistic defaults you will most likely have very noticeable phase issues. If you manually correct the distances, you may correct the noticeable phase issues, but it will still not sound right. This problem may be because there are driver phase/group-delay correction issues that cannot be corrected by manual relative driver-distance manipulations alone. Remote subwoofers are a different story and may need manual relative distance intervention. I’m still looking into the best way to deal with remote subs. Any suggestions in this area are certainly welcome.
I my case I was able to effectively block the rear sound wave from my Apogees with a heavy sound-absorbent blanket similar to what you would find in under-hood sound insulation in a automobile but of higher density. Please don;t ask exactly what it is or where I got it, it just appeared in garage one day, but any heavy-weight sound absorbent material such as a heavy quilt should work just as well. Just be sure to position the material in such a way in order to cover ALL of the rear of your dipole speaker. As I understand from our conversations, due to the exceptional acoustic transparency of the Solundlabs and probably most other ESL speakers as well, mijostyn informs me that simply blocking the rear of those speakers with a quilt was not enough and for this reason, he is building a Sallie for his unique situation.
Finally, be sure to remove the rear covering before starting step 3 since in this step acoustic properties of your entire room are quantified from your listening position.