More power for better sound at low volumes?

Power alone has perhaps the least of anything to do with low volume sound quality. Almost everything else matters more. THere is lots of good info in threads scattered about here on A'gon already about what goes into getting good sound at lower volumes. Best to go through some of that first and then ask more questions here as needed.

I tried finding ideas on a-gon, but I must have used improper search parameters.

I forgot to mention I use Martin Logan Spires, effeciency at 91.

I'd guess that your present speakers couldn't use all of the power presently available to them with your amp, and even if they could you would leave the room or loose some hearing! :-)

Personally, just on principal alone, if I were in your place I would look about for a very high quality low(er) power, high current, Class A amp. At least one highly esteemed amp designer/manufacturer has long proclaimed that its the first watt that really counts.

BTW, in my experience, quality low volume sound levels are more the function of the speaker than anything else. A lot of speakers really don't open up until they reach a mid level volume regardless of the amps used. Both dynamics and electrostats/panel speakers anyway. Don't know about horns but they don't take much power anyway.

At least one esteemed amp designer/manufacturer has long proclaimed that it's really the first watt that counts.

The amp designers who post here would be best-qualified to answer your question. But it seems like full sound at low volumes is, at least in part, a design intention. For example, Bryston says of its 28B-SST2:

A significant part of the design criteria for the 28B SST2 was to develop a very powerful amplifier that would drive any speaker on the planet but maintain an ideal power curve at 1 watt as well as at 1000 watts and every power level in between. Most amplifiers exhibit a power curve whereby the best noise floor, drive capability and distortion is maintained from about 1/3 power and up.

The Bryston 28B-SST2 Mono amplifier maintains its power curve right from the first watt. This results in a BIG POWERFUL amplifier that sounds incredibly detailed and musical at very low levels and maintains that same sophistication and drive capability with even the most difficult, inefficient speakers, large or small.

Is this merely marketing copy? Maybe. But they do sound both full and delicate at very low volumes, and maintain their tonal balance irrespective of volume levels. I'm not sure how much of that's attributable to their brute power, but the literature suggests not all of it.