Has anyone replaced tubes in Aesthetix Rhea ?


I have developed a high pitched hiss from the stock Sovteks which came with my unit. I believe its at least two or more of the 12ax7s which are in the first input gain stage as I hear it more or less equally out of both channels. I was wondering if any Rhea owners have rolled the tubes in their units and, if so, what prompted the swap and what success you have met with.
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Just wanted to share the tube compliment I came up with. DEAD quiet, nice sparkle on the top, holographic soundstage and very nice air around the instruments.

V1,V2 & V3 - Sylvania 12AX7
V4 - Brimar 12AX7
V5 - Amperex 6922/6DJ8 (1961)

All NOS, matched pairs. Took a few months but worth the challenge.
After several testing sessions I would also like to share a solution I am very happy with. Minimum noise, excellent transparency while keeping a full bodied sound with huge soundstage:
Single Ended stages (2): Telefunken ECC83 smooth plate
Phase converter stage and amp stage before 6922 (2): Telefunken ECC 83 ribbed plate
Buffer: Siemens ECC88 gold pin.
When I first started to play around with the Rhea, I liked the all Telefunken route. It was good enough to convince me that I needed an IO which I did purchase.

I did find another tube set I like better and it's cheaper to boot. In the first gain stage (v1 & v2), NOS EI's from vintage tube service. In the second gain stage, GE black plate 5751's and for V5, a Telefunken 6DJ8.
Dear Sbrown, Was just passing by and saw this old thread. With regard to your chosen tube complement, just be certain that the "second gain stage" does not lie within the RIAA network, because the electrical characteristics of the 5751 are not identical to those of the 12AX7. Thus using a 5751 would alter your RIAA correction. (But perhaps this has had a sonically pleasing result, by chance.)

Aesthetix can tell you whether this is an "acceptable" tube substitution.