Without a doubt, the TFK ECC83 is one of the truly great tubes of audio. It transformed my vintage Quicksilver preamplifier, too. I have four of them in my stash since the 1970s. I use one each in the phono and linestages. (The Q uses one half of each dual triode per channel, for stereo.) You guys have me just about convinced that I need to try a VTPH2. The circuit and the construction look like nothing special, but this may be a case where the whole is much greater than the sum of the parts. (Actually, the Quicksilver full function preamplifier that I am using in my second system also fits that description.)