Having lived with, on extended periods, original Quad ESL-57s, Stax F-81s, and Apogee Stages, I would say each of these wonderful speakers have their merits. The Quads were beautiful in a narrow(mid-band) range; the Staxes were natural yet fast and soundstaged great(though somewhat miniturized). Both of those sounded fabulous with tubes, though the Stax needed a lot of power so I usually used hybrid or SS amps(with tube pre-amps). The Apogees are incredibly life-like, startlingly so at times, and this while using SS electronics(Krell my preference). However, I believe they use a second order crossover, meaning the tweeter and woofer are out of phase with each other. It really bugs me on recordings where the absolute phase is reversed, especially because this speaker is so transparent and revealing. I've been through a ridiculous number of speakers recently, but I long to own a set of Krell-driven Mini-Grands(I currently have Stages and Centaurs), though Divas w/Dax are so good it hurts, and a friend's ProAc Future IIs(dipole midrange with ribbon tweeter) are just plain spooky in the midrange.