For what it counts... my thoughts about this "Gold/Platinum grade- Low noise and microphonics-preamp tube" staff.
Meybe I read it all out wrong way but seems that you are trying to say that 50 cheap tubes "(Driver Grade-suitable for the output buffer stage of a DAC or CD Player)" are somehow less good than few well known high-grade tubes. Well, firstly, in case of Aune T1, those "(Gold/Platinum grade- Low noise and microphonics-preamp tube)" are acting same way - "suitable for the output buffer stage of a DAC" because that`s what Aune T1 is - an tube buffered output stage SS DAC, so in that point, there`s no difference. Imho, this "low-noise & microphonics" is irrelevant in this buffer stage.
Have no issues with my cheap tubes collection in that part. There are 1 or 2 tubes that are making slight "hum or hiss" when nothing is played and volume is turned to max but again, it`s irrelevant when music is playing, you just can`t hear it and you certainly won`t listen @ max level. And if someone does, then he/she has probably already damaged hearing and won`t hear it anyway.
From my point of view I would certainly prefer hunting low priced tubes than buying 1 or 5 super-duper-hyped-high-grade-cryo-treated-gold-pin-tube. Not saying they are bad but you can never
rely that it will suit to your hearing or cans or music or taste. Of course they have greater audio imaging, separation etc. than most of tubes ...but ...for example, I have this Amperex 6GM8/ECC86 and it is just awesome "holographic" sounding tube, but - does it fit for every genre I listen? No actually. Most of the time I still prefer Amperex OG 6DJ8 steel pin for progressive metal/rock/jazz (which is actually preferred by many over gold pin high-grade tubes depending on gear being used, music genre etc.), because it brings guitar riffs more into "play" and has better "front of stage" imaging and it is slightly better fit for my cans & tames Aune T1 bright sounding amp part also. Like I told there are many nuances that come into play and thinking that "I will buy gold pin high-grate tube and everything is up to its best" may not work (and probably won`t for many). Another example... many prefer "old sounding", intimate, warm, grainy etc. tubes with old rock/acoustic or other more specific tastes or genres - you just can`t have it with "holographic" sounding tube - as awesome as it might be. I have 4 or 5 of these intimate, warm etc. tubes that sound great with old rock etc. but it just isn`t for my taste and I don`t listen much this kind of music but those tubes are certainly worth having.
I think for ppl that listen very many different genres it is much better to hunt cheaper tubes, read impressions and find good match for they setup than buying 1 "top-notch" tube (for different reasons and nuances I just told about). They can get them cheap, have fun with large variety of tube types in area that is largely undiscovered PCC189/PCC88/ECC189/6GM8/PCC85 etc.
Like I told, I have already found my favorite tubes for different genres. It`s just interesting and fun to explore and also invest into some rare tubes that might be even more expensive in the future
than those gold-pin high-grade tubes.
For the end of my 5 cents...
Everything that glows isn`t gold ! (I mean gold pins & high price in this context).
Have fun with you high-grade tubes and hope you like them. Still looking foward to 6N27P impressions
Over and out!