@tony1954 the speakers are positioned to beat interact with the room, but that also matters on what comes out of them, where an amp has a profound impact. Often in an upgrade path, a person may replace their amp with one that delivers more across the spectrum, added harmonics / richness, stronger bass due to amp confidence and control, etc. Sometimes it may be necessary to adjust the speaker from this. Sometimes, it is slight, and other times, it is more profound.
To add to my previous posts, amps are not always linear. And more so, how they interact with a speaker given the speaker’s impedance may affect its linearity. So if the sound output shifts, the way it interacts with the room also shifts.