Just found this thread!! My instructions show 0db or -12db. All my gear is boxed so I can't ck setting right now but will early next week. Aren't you using 10M's and Amperex PQ and feel the 12AX7 sockets provide the most noticeable change ? Sorry I can't recall with certainty. I also am experimenting with tubes currently using Mullard CV 4004 Box Plates and Amperex PQ white label, but have just bought; Amperex milspec 7025, National 5751( Sylvania) black plates triple mica cryoed, Amperex BB 12AX7, Rca 5751 black plates black plates Telefunken Smooth plate (w/ diamond) plus a few for the 6922 socket. I have my fun cut out for me!!!