Most people do not have built-in SPL meters, and the subjective perception of loudness is not accurate at all, especially without very fast switching between sources, and it can easily be biased as well. It may sound stupid, but loudness and sound quality are indeed often confused, and the "volume knob bias" does exist; why do you think so many people hear higher gain - even higher digital gain that would give exactly the same sound with the volume control adjusted to match the level - as "better" sound ?
That would happen in an ideal world. In reality, audiophiles rarely match volume for the purpose of subjective comparisons by measurements, typically only by ear, and the levels can therefore be "off" by several dB. If you tried to compare it yourself, you would find that reducing the volume by even 3 dB is not that much of a loudness difference, if there is a few seconds of silence while switching, but it does sound "thinner" and "flatter".
You might be surprised at how many newbies use the O2 at high gain because it sounds "better", and then complain about the clipping.
Right on about volume bias STV. "Volume" can be added to music in many ways - recording, amp, speaker efficiency and tuning. What is so annoying is that this often means clipped recordings, clipping amps, clipped pre-outs, and on and on. I don't know what a pure listening experience is anymore, other than an acoustic concert with an audience of 1 in my backyard.
I also don't get why people are confusing volume, gain, power, SPL, and subjectivity so much. Controlling for all other factors, more power does not = better sound. It = more SPL, an objective, dispassionate fact.
False. Check the equal-loudness contours. The louder the sound we hear is, the flatter our hearing frequency response gets, especially in the bass. This is why all of Headroom's lab measurements are done at 80dB and then equalized to compensate for curves at that volume.
It has nothing to do with power, it has to do with our ear canal resonances.
I am aware that human perception of sound is not "flat", and that our ears, being optimized for the frequencies of speech, require higher SPLs at certain low and high frequencies in order to create what is "to our ears" a flat response. But this process of adjusting for a perceived "loudness curve" is not done by amps. It is done at recording or post-processing levels.
This does not mean that more power = more or "better" bass. That is still false. More power = more SPL. You are assuming that volume, gain, and frequency response are all carefully controlled at the amplifier level, which is wrong. You are also assuming that loudness is always considered subjectively superior - do you have grandparents? Either their hearing is shot, or they would never in a million years go to a concert. Compensation for our natural hearing deficiency is also controlled at the recording and speaker level. An Amplifier *should* have a flat frequency response at all power levels, because its job is to take a signal, add gain or amplify it, and output that signal through a speaker. The speaker, being the most distorted piece of the audio chain, will play it back at whatever frequency response it has.
I think you misunderstand that two amps, of two different power levels (e.g. 50 watt and 100 watt), volume matched, all other things equal, will sound the same. One difference is that the 100 watt amp will, in theory, provide higher SPL. The increased volume, according to you, "will sound better". So, you are conflating SPL with sound quality, which is wrong. I thought my point was obvious, which is that more amp power is more power, not more "subjective enjoyment".