He meant Frequency response in room is highly depending on where you put speakers and where you listen.
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Yes, correct .
Good installation with the two loudspeakers in the specific room is much more important than putting them randomly in the room , or were it looks good .
You can get maybe 80% better soundquality doing this right and at the same time using acoustic damping and diffusing. Using dsp can get you the further 20% , but its important to do it the right way - never start with dsp corrections from listening position - start with finding the best loudspeaker placement , where they sound the best without any correction at all, and were they are most pitch accurate = less boomy with good definition of the base and most believable and natural sounding . This is done best with your ears because there is no way to measure a perceived stereo soundstage with a microphone .
10 cm distance difference between the two stereo loudspeakers placement in the room can change both the perceived soundstage and the measurements.
Installation of two stereo loudspeakers are important because of the flawed stereo system , the impact of the room and because we dont listen to one speaker in a mono setup. ( unless you are in the kitchen having music as background ).