Newbie with beginner budget and love for lower bass freqs undecided between BR03 and DBR-62

[dominikz]

I didn't say an amplifier "exteded" speakers response, but "improve" its bass both in quantity and quality. I believe a subwoofer may not necessarily be a fix for lack of bass from a speaker. A subwoofer extends a speaker response when properly amplified, but it can't improve the bass from a speaker.

The issue is that these kinds of statements require some kind of qualification to be meaningful to people who haven't shared your experience. To my knowledge an amplifier can influence the bass response in two ways:

1. If the amplifier cannot produce enough current for the attached load at the required voltage it would clip (or possibly shutdown, depending on protection circuit behavior). This should be very audible (extremely high distortion or no sound), but I suspect it is quite a rare occurrence with loudspeakers such as Elacs, unless quite loud SPLs are required (or the amplifier is very low power).
2. If the amplifier has very high output impedance its frequency response will be modulated by the impedance characteristic of the connected loudspeaker due to simple voltage division. This would be a subtle effect (usually a fraction of a dB difference, up to 1dB in pretty severe cases), which can actually completely be compensated for by PEQ so it is not really a practical concern when room EQ / DSP is used. I wrote about this several times previously, for example here and here.

Has anyone cared to measure a speaker response from two different amplifiers? Because theoretically you may end up with better correction/linearity/subwoofer integration depending on which amplifier you use.

So far I've personally never encountered any differences in perceived bass quality with any of the several amplifiers I tested in my system, nor seen any meaningful difference in in-room measurements - especially not after they were EQ-ed to the same target.
But it would be great if you can provide examples of such measurements with an amplifier you believe results in bad quality bass and one you believe results in good quality bass with the Elacs. In-room MMM measurements with 50dB vertical scale and 1/12 octave smoothing should be a good start.
That way we'd have some objective data to anchor further discussion on.