I owned an Xono for several years and compared it with the Audio Research PH7, a hybrid JFET+tube phono stage that is a bit more expensive. My take on the Pass unit is similar to Barrysandy.
As others note, the Xono is solidly constructed and very quiet; it boasts flexible impedance and capacitance loading and has plenty of gain - up to 76dB. In my system it offered a spacious soundstage with an airy sense of venue context. Low end transients are firm with a nice sense of weight and impact. Music through it has punch and drive, probably due to a nice power supply. I would not characterize it as cool or overly incisive and found it particularly well suited for rock n roll.
What I heard by comparison is the Xono is not as harmonically nuanced as the PH7. From it and other tube based units I hear instruments and vocals with better mid-note tonal development and better decay. Through the Pass unit, percussion such as bells and triangles or upper frequency brass could be a tad glassy and occasionally come forward. Overall, the PH7 offered more life-like harmonic information with less smearing, which meant better instrument articulation and separation.
Be that as it may, I really liked the Xono. As they say, you pays and you gets: a used Xonos in good condition under $1.7k would be a great value. As for new, if you don't need more than 60dB of gain, at ~$5k, the ZYX Artisan would be a v. strong solid-state competitor that doesn't sound like solid-state. Its a smallish unit that doesn't get much press, but well worth a listen. If you can go up a notch, the PH7 is superb.
