need help on transparent sounding 12au7 tubes

The Clear top should be in that "neutral" zone in most applications - and much cheaper than TF or Siemens. Glad it is working for you; you can drive yourself crazy rolling NOS and miss a lot of music while doing so. You might also want to try the RCA Black Plate version, again, much less than the Europeans.

Tvad, ever compare the RCA 5814 with the 12au7 Blackplates (1954 or thereabouts)?

I agree with Mofimadness and Tvad. I've tried many different combinations of 12au7s and 12ax7s in the 9 pin sockets of my Air Tight ATM-3 amps. I keep coming back to those airy, easy, musical Mullard cv4003(12au7) boxplates. In conjunction with the transparent sounding Ei Yugo pre-war 12ax7 smooth longplates, (made by the Yugoslavs with the Telefunken equipment and supplies they had puchased from Germany),they provide a wonderful sound synergy. I get essentially the same enjoyable results with the Yugos OR the German made Teles, but the Yugos are considerably less expensive.