Has anyone replaced tubes in Aesthetix Rhea ?

Stew, if your Rhea is less than a year old, check with Aesthetix about replacements. They guarantee the tubes for a year. The first gain stage will be the place to first hear some noise as the tubes age. These first gain stage tubes are very critical given the extremely high gain being delivered by this phono stage, and the stock tubes for these positions are hand selected at Aesthetix for low noise. If you decide to try vintage tubes for the first gain stage, be sure to get some help from one of the better dealers who can match for very low noise, like Andy Bouwman at Vintage Tube Services.

I own an Aesthetix Io Signature and have been running it with stock tubes for the past four years. Many people suggest Telefunkens for the 12ax7s in the Io, and I suspect the same would apply to the Rhea given the similarity of the circuits. Others have liked the French Mazda long plate tubes. Both are fairly expensive. Just last week, I finally tried rolling the 12ax7s in the Io's second and third gain stages, just to see what a set of Telefunkens would sound like there. I'd used Telefunkens in a previous phono stage and liked them there. So far with the Io, the jury is still out: mostly a negative change for me in terms of resolution, transient response and tonal balance. I'll additionally try changing out some of the other tubes (a 6922 and a 6sn7) before taking out the Telefunkens, but at this point I don't have nearly the great sound quality that I did have with the stock tubes.

One truism about rolling tubes: you WILL get a different sound. May be improved sound, may not be.

And I still want to experiment with the vintage tubes because I believe some combination of vintage tubes is highly likely to sound better than many of the current manufacture tubes, as described once again by Albert Porter in a recent post on the cost of NOS tubes.
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Rushton:
Thanks for your thoughtful and detailed response. Oddly enough, the noise I was hearing was not present last evening. I would not think this so strange, except the hissing sound was heard on at least three consecutive days before that. I'm almost scared to go home tonight and see whether it has emerged again. Of course, the noise did not go away before I ordered a quad of Telefunken 12AX7s off ebay. I haven't decided whether I'll swap them out as soon as I receive them or if I'll wait for the problem to present itself again. I'm beginning to wonder whether the problem is with the unit and not the tubes, since I can't imagine a tube going bad then miraculously repairing itself. I did not listen for very long last night, so the problem may be heat or thermal sensitive. I should have a chance this evening to give the Rhea a decent workout. I am curious to see what change the Telefunkens will bring. BTW, the people at Musical Surroundings wrote back to me indicating that some people have had good results replacing the 12AX7LPs with GE 5751s. Might try that if the Teles don't do the trick. Anyway, I'll keep you "posted".

Hi Stew, glad to hear the hissing sound was not present last night. In my experience, tube noise can be intermittent - from one listening session to another. It can be a little unnerving. I've made a practice of taking a deep breath, powering down the system, and coming back a few hours later or the next day. Sometimes the noise completely disappears, sometimes not. I once lived with a really irritating noise in a driver stage tube of my amplifier for a couple of weeks, then it completely disappeared and never came back. What you're hearing is more likely an intermittent problem with a tube than a problem with the unit itself. Good luck, I'll be interested to hear how your journey progresses.

"...since I can't imagine a tube going bad then miraculously repairing itself."

And, funny thing here... The system is sounding better late last night and again tonight with the Telefunken 12ax7s still in place. Maybe the 15 hours of playing time leading up to a "critical" comparison listen was not enough break in and the additional 10-12 hours is making a difference for the better. We'll keep an open mind and see how things play out.
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I had what might be a similar situation with my Rhea. From time to time I would hear a short duration hissing or rushing sound, but only from the right side. Of course my first reaction was to suspect tubes. During one night of experimentation I changed from XLO to Quatro-fil interconnects between my Rhea and pre just to see how this might change the sound from my turntable. I have not heard the noise since and it has been almost a month. Kind of interesting but probably not what you're experiencing.

I do have some Mullards on my list of tweaks to buy in the coming year.