I have the Sonic Frontiers Line 1 which I bought off a fellow A'goner. I am very happy with it. Parts Connexion does mods and repairs of these units. I would stick with one of the Line series pre's if you are going with SF as I've heard tell that they are much better than the previous generation of SF pre's. The Line series of preamps have a more graduated volume control than what Doug describes above. It goes in half dB steps from zero to 95. Average listening for me is around 44 to 60 depending on the source CD and my mood. Would like to have taken it higher but I live in an apartment and don't wish to move yet. Good luck.
