Many tube phono stages are inherently noisy and there's not much you can do about that. There are only two ways to dramatically reduce the amount of noise (hiss) relative to the music signal. First is to use a quieter phono stage, like the Lehmann Audio Black Cube, which is a good way to go. Second is to use a cartridge with a substantially higher output than the one you are presently using. I believe that the Grado Platinum you're using is a high-output model and you may not find anything suitable with a substantially higher output level. Another possibility is that there may be something wrong with the circuitry of the phono stage (not the actual tubes -- perhaps bad/noisy resistors?). You shouldn't be hearing much tube noise with a high-output cartridge considering the Dyna 70 amp and Paradigm Studio/80 speakers you use. If the particular Grado you're using is in fact the high-output version, I'd send the preamp back to Rogue to check the phono circuitry for possible noisy parts(other than tubes). Good Luck!
