More power for better sound at low volumes?

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.

I tried filling my listening room with a gas to see if it made any difference, but I passed out before I got to hear anything.

This topic is almost meaningless if you can't specify exactly what constitutes "low volume" or "high volume" as these things are relative to the individual actually listening (except regarding extremes in level like REALLY LOUD or REALLY SOFT)...Also, do amp designers really design to a "sweet spot?" Does that spot adjust to musical dynamics? Isn't the wattage rating absolutely subject to speaker load? Isn't it obvious that a speaker with recessed treble and/or bass will seem to get quiet quicker with lower level? Where am I? I'm frightened now...

Upper case letters are clearer at low volume.

I've had giant horn loaded speakers and small bookshelf speakers...at the same low volume level they both are low in volume, and things aren't as audible because they just aren't. That's just the way it is, and one must learn to accept it. Or not.