Pass Labs Xono vs. Aesthetix Rhea

The Aesthetix like most all tube phono stages is noisy with very low output (.2 to .3mV) cartridges.

The Xono has state of the art low noise, and high gain (up to 76 dB). Also has more resistance loading steps, and range than any other phono stage, to fine tune any MC cartridge.

The Xono is NOT sterile sounding, but very transparent, slightly warm, and natural sounding!

I also disagree that Xono is sterile and cold. I have not compared it to Aesthetics, but compared to Hagerman Trumpet, and MFA Luminescence. While both tube units do sound warmer and have subjectively a bit more "life", they also luck in control, accuracy and definition. Plus, they need a step-up, and even arguably the best (I have a TX103 copper based unit) introduces distortions and colorations. MFA has enough gain to pull even a .3 mv MC, but noise is high. Even with the AT OC9 in my system Xono does not sound sterile and cold. I guess this may be system dependent.

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.

For something in between those two, how about the EAR 324 or the EAR88pb. Lots of raves for these 2 phono stage.
It would be of help if we also know what carts you plan on using them with.

Also consider your pre amp. My understanding is that Aesthetix has rather highish output impedance (true of most tube phono) and it does not like solid state preamp very much ( at least those with 10k input impedance like Spectral, ASR etc). I recently tried Io Signature with my ASR integrated and they did not match well at all. If you have solid state pre with 10k ohms input impedance, most likely Aesthetix will not be for you. Recently I tried Fosgate Signature phono and it works very well with ASR. In the Fosgate manual, it stated that its output impedance is low enough to drive solid state pre with 10k ohms input but did not say what the actual output impedance is. In fact, it sounds better than Io Signature that I tried but this does not mean that Fosgate is better than Io Signature, just that Io Signature just does not like 10k ohms input impedance very much. I believe Rhea has similar impedance pattern to Io Signature.