I think this might be the least useful of all the advice here...
The first "revelation" speakers for me were my Voigt pipes. (I built them based on Derek Walton's Voigt pipes.) Used them for two decades until the surround gave up. (Cloth surround.) These are so-called "Full range" speakers with a single driver (Fostex FE-204) that in my application (system & room) gave a 30Hz-18kHz response. While that seems as a joke to many, what is no half joke is the integrity of the sound you get from a crossoverless loudspeaker. Coupled with a Darling amplifier, I had as much joy with it as humanly possible. It took me from the slicing sausages attitude of gear comparison to embracing music into my heart and soul, and the night turned into sceances instead of the love/hate listening sessions we are used to.
Second paradigm shift: the Voice of Lancelot speakers (which are my creation), which despite two way have the purity and serenity of single driver speakers - with deep bass (and infrasonic bass) added to the mix along with the ability to play so loud to put the fear of death in me (and that volume without listening fatigue). These two have opened up an entirely different range of experiences.... it needs not play loud, I usually listen moderate / quiet, but can cover all the experience ranges when that's what I'm looking for....