Thanks for the explanations everyone. I am fortunate enough that my Chenin, after making the initial mistake of swapping tubes right away as soon as I received it, only had one small issue since 2004. I have this paranoia about the R channel on the phono a little lower in output than the L channel at identical gain pot settings. I wrote my concern to Mick and he sent me an schematic diagram to measure the voltages and make proper adjustments. After that, it's been working fine (knock on wood as I type this!) so far without hum or hiss for almost three years now.
regards
regards