@amir_asr ,
Quick, tell me what frequencies in this graph are room modes, and which are boundary issues? Hint, there are some obvious ones that the Lyngdorf was not able to do anything with that are the boundary issues and those absolutely can be improved significantly with proper use of acoustic panels. That is simple physics. You are correct that multiple subs won’t get rid of your room modes completely, but they will soften them considerably and present more consistent bass across a larger listening space whereas room correction improvements will be more localized.
As a point of information, what Ansi-CTA-2034 uses for Front Wall and Rear wall is opposite what most audiophiles will call the front and rear wall. In 2034, for instance, the front wall bounce is the spatially average 0º, ± 10º, ± 20º, ± 30º horizontal responses and 0 degrees is pointing forward from the speaker, so when looking at the speaker, it is what most would consider the back wall. The Rear Wall Bounce is what most audiophiles call the front wall reflection, hence why it declines rapidly at high frequencies due to the directional nature of the speaker at higher frequencies. The rear wall bounces is the spatially average horizontal responses at ± 90°, ± 100°, ± 110°, ± 120°, ± 130°, ± 140°, ± 150°, ± 160°, ± 170°, 180°.
Due to precedence effect, the on-axis sound, and not the reflections rule predominantly what you hear. And this is naturally not impacted by the room (above transition frequencies). What reflection there is, gets attenuated due to much longer path length of that front wall.
This is of course correct.
Also correct is that the early reflection graphs are spatially averaged over a large number of angles and hence both masks acoustic interference, both constructive and destructive and provides no weighting for angles that may be more or less relevant in a given room, speaker position, listener environment which can impact acoustic interference as well as timing and intensity as it relates to early arrival reflections that may interference with the precedence of the direct sound.
A case in point is the room response curve you posted which has clear boundary interference, however, that would not show in a 2034 report. Nevertheless it occurs, it is audible, and it can be addressed.
The second issue not readily evident in the room response though there are some indications is the strong reflections from the very close side walls that will arrive both close in time and relatively high in power compared to the direct response. Yes it is correct that your speakers are well designed with smooth off axis response hence this won’t cause any weird tonal issues making assumptions about your wall materials, but back to the precedence effect, it will affect imaging, and while side wall reflections can make the image seem more expansive and the result pleasurable, when the wall is that close the result is invariably negative. You may not trust audiophile listening reports, but in similar situations, almost without exception where an audiophile was required to place their speakers near side walls, the addition of appropriate acoustic panels resulted in a significant perceived improvement. Anecdotally, you will not find a large professional studio with speakers placed that close to a side wall without use of acoustic treatments.
I won’t say it is universal, but it is almost universal that treatment of first reflections in a small rooms is recommended by professionals. Unfortunately, there has not been extensive research on this topic to draw on and what does exist is mainly around speech intelligibility, however, Brett Leonard in his PhD dissertation did some excellent work showing effects of a rather early intense reflections on perception and even the variability of that perception across music genres. Your position does not appear to be based on the fundamental science, available research, or professional recommendation.
....