Tvad writes:
Well, I'm of the opinion that it matters based on what I've experienced in my system using speakers that had an uneven impedance curve.
Relating back to what Unsound stated in his previous post, the reduced power output into higher loads (lower impedances if I'm reading Unsound correctly) from an amp that does not double down (double power as impedance is halved) resulted in a sound that was always "bright" because less power was being delivered by into the mids and bass frequencies than the treble frequencies. Therefore, there was a higher decibel level in the highs than in the mids and bass. The difference was not large, and it probably wasn't noticeably measurable on a Radio Shack decibel meter, but the results were clearly audible on my speakers that had an uneven impedance curve.
Once I drove them with an amp that doubled down, the sound was evened out and the speakers no longer sounded "bright".
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Sorry, but this is pretty basic misunderstanding of how amplifiers work. An amp with a low output impedance does not have a frequency response that varies with a speaker's impedance. The key parameter that varies is potential current delivery by frequency before clipping occurs. So for a good voltage-source amp with 100w into 8ohms, if the speaker has a peak impedance of 16 ohms into 4KHz the amp will clip at 50w, and if the lowest impedance occurs at 40Hz with 4ohms the amp will clip at 200w, but the frequency response at 50W will still be flat (within the amp's spec) across the entire spectrum up to 50w.
Trick question - what happens if the speaker is reproducing 4KHz and 40Hz *at the same time*?