What makes a speaker sound great at low volume?

My experience shows me that good interconnects and especially an upgraded power cord (nothing crazy here. Say $50 for each set of phone plugs to get decent quality plugs and say $75 for the power cord. The Pangea cord from Audio Advisor is very good). People tend to go crazy here but there is a point of diminishing returns of dollar to sound quality. My point is being-to recover as much detail as possible which fleshes out the music at lower levels and does improve efficiency as well. Speaker placement through trial and error, assists greatly to produce a solid sound stage where getting the tweeters at ear level is important.  Smaller speakers, say between Dynaudio to Def Tech 800s are great with a quality subwoofer.