tube amp sound more engaging

Hi folks, can you explain why everytime I listen to high efficiëncy speakers, like old Klipschorns, powered by not-so-expensive single ended tube amps, the sound is more engaging (largely due to greater immediacy and presence) than when playing the same music through expensive high-end solid state amplification (high current, high powered design, with the most sophisticated switch mode power supply, etc.) and a pair of very accurate, high tech loudspeakers. This is not funny, because the much older and far less expensive system makes more musical sounds than the so called state-of-the-art and ultra expensive high end stuff.