More power for better sound at low volumes?

A good set of headphones is your answer.

A lot of vintage gear used to have loudness controls and other tone control features that due to how the human ear works were useful at low volumes sometimes but required manual interaction to activate/use.

Its possible that this could still be part of an amplifiers design, ie internalized auto equalization in essence for the purpose of optimizing sound at all volumes.

Sounds like at least a couple makers might do this but do not know for sure. Some might advertise as a feature or some might keep it under wraps so as not to offend audiophiles that object to equalization solutions but like good sound at all volumes.

IF done well, I think this could be a good thing/feature if any makers want to fess up?

A Audio Research LS9 is the answer.

The fact that any good system sounds different when playing at low volume usually has zero to do with the system, and everything to do with your ears and your brain. The spacial cues provided by treble get lost, and the bass stops interacting with everything...clearly a good, even response system does sound better than a crappy one at all levels and obviously a near field system can play lower and retain fidelity because it's closer to your head. Remember, sound is made of waves travelling through the dense air in your room, to the dense brain in your head. I prefer that amp designers not put any low level frequency boosting in my amps, and I can reach for the damn headphones if I need 'em.

Good points by the Wolf man.

Differences in sound at low volume may have some to do with the system, particularly the speakers, but yes a lot to do with you and how room acoustics work.

"sound is made of waves travelling through the dense air in your room, to the dense brain in your head"

My listening room and I both resemble that remark!

Also I realize now that a pressure controlled listening room might be the ultimate tweak, though more costly than fancy fuses. Anybody out there have one of those?

In all seriousness, I truly do think that my system sounds better on high pressure weather days than on low ones at all volumes. A scuba suit with acoustically transparent ears might also be required for the ultimate tweak to go along with the pressurized room!

Also in all seriousness, has anybody say in a mobile home ever a/b compared their system set up in the mountains at high altitude (lower air pressure) compared to down in the valley at lower altitudes/higher air pressure? I would expect some differences.