need help on transparent sounding 12au7 tubes

You will have NO problem finding low noise/non-microphonic NOS tubes. You just have to shop with sellers that know how to test for such things. Kevin Deal is one of those that is most fastidious with his testing and grading (http://www.upscaleaudio.com/view_category.asp?cat=44). If, by stating, "transparency", you are saying, "no colorations": then you don't want anything British. They will impart an unnatural warmth to your presentation. Siemens and Telefunken are the most transparent, of which the ECC802S would be the ultimate. They were ECC82's, specially selected for low microphonics/noise, linearity, and triode balance(and cost accordingly). There are no new production tubes that can come close to the reproduction accuracy of a properly selected pair of NOS tubes. The exception to that rule in 9 pin miniatures are the EAT tubes (http://www.musicdirect.com/product/73403). There again- You WILL pay for the quality. They don't manufacture a 12AU7 unfortunately.

It's been my experience, over the years, that any equipment with nine pin Mullard or Brimar tubes installed had an added warmth, sugary glaze or "tubey sound"(as the originator of this thread put it) that simply does not exist in live music. Said coloration was easily eliminated when the tubes were replaced with those of German manufacture. What others may prefer/enjoy/seek in their sound does not concern me, as Scar972 asked about "transparent", "detailed" and "resolving" tubes. I replied based on what I know to be true. Scar972- Kevin Deal at Upscale has a great amount of experience with the tubes that he sells, in a wide variety of components. Call, and ask him for suggestions regarding the presentation you'e seeking.

Tvad, I recently changed rooms to a smaller, nearfield presentation. I had used the Mullard CV 4003 in my PrimaLuna integrated amp and felt the sound was to "warm" in my old room. With the new room set up and the same equipment I tried the Mullards again. Wow, I now know what the hype is all about .