High efficiency horn loaded + EQ, either software based at streamer or analog piece between DAC or pre.amp and amp set to compensate for fletcher-Munson curve noted above. I often listen at low volume and have a Klark-Teknik DN-360 between DAC and integrated amp feeding Klipsch horns. Sounds very full and alive at low volumes. When I turn it up louder, simply disengage the EQ or turn boost way down. Works great.
With your budget look at Volti horn loaded speakers.