Amitm,
I believe that BrianM is correct on the gains. They are an industry standard. The volume pot at it's minimum position actually shorts the selected source input to ground. At full rotation, the full signal source is then passed to the preamp line stage. The volume pot is before the line stage, which has it's gain fixed at 20dB. The gain of the preamp, or power amp for that matter never changes. It is fixed, i.e. constant. Only the volume potentiometer "taps" a portion of the signal somewhere between 0% (shorted to ground) and 100% (full clockwise rotation). Volume pots are usually (almost always) logarithmic as opposed to linear. This is due to the way that the ear responds to volume. Anyway, the level of signal tapped from the volume pot is fairly gradual for the first half of rotation or so, increasing rapidly as it is increased. If it were linear, half rotation would produce 50% of the signal. Rest assured, you'll have plenty of control over the gain of your system. Hope this helps a bit.
Brain, I haven't forgotten about the U70 loan. I just re-tubed with a fresh set of EH 6CA7 power tubes and new 5AR4 rectifier. I wanted to listen to the pair bridged driving my B&W 801FS loudspeakers. I should get around sending it to you after the holidays.
Ron
