As of this writing, the Aesthetix are the best preamps I've heard-and by a considerable margin. Indeed, the Callisto and Io are, given the caveats I've enumerated, landmark designs, like the ARC SP3a-1 or SP10 MkII-preamps that open a new horizon line, particularly with LPs. To put this differently, as my friend and former Fi contributor Steve Sullivan did when he heard the Aesthetix in my system for the first time, ''It's like I've never truly heard stereo before.'' That about covers it. This review includes a review of Aesthetix's Callisto Signature Linestage Preamp.