There are many factors that play into this. It's complex. Suffice it to say, I would look for a low wattage ultra amp, like the Threshold SA3.9e, a class A 60 watt stereo amp. These low wattage ultra amps are designed to sound there best - the sweet spot, soundwise - at much lower levels as compared to higher wattage amps, which have a sweet spot a bit higher.
Case in point, the SA3.9e had fully body, detail, etc. at a much lower wattage. This is part of the design parameters of such an amp. Now if you compare that to the SA6e monoblocks, rated at 125 watts, they have to be pushed to higher levels to get the same body, details, etc. Because that is its design parameter.
Case in point, the SA3.9e had fully body, detail, etc. at a much lower wattage. This is part of the design parameters of such an amp. Now if you compare that to the SA6e monoblocks, rated at 125 watts, they have to be pushed to higher levels to get the same body, details, etc. Because that is its design parameter.