More power for better sound at low volumes?

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.

Yes big power = nice low volume listening. I also totally agree with Lloydelee21 that lower noise contributes to low listening accuracy. With each upgrade I've made, all of which lowered the noise floor, the volume knob was reduced for much of my listening. Before replacing my 500 watt amp with 1200 watt monos I suspected I might have to play at least at a moderate level to perceive a balanced performance. I couldn't have been more suprised when the higher powered amps sounded great at well under 1 watt on the meters. This is no doubt due to the lower noise and balanced power delivery high power amps can deliver at all levels.

I have found the most engaging sounding amplifiers to be those with lower power. Just my experience.