So I just recently purchased a Road King II, after joining a new band. I read that you can get the exact circuit of a Dual Rectifier on Channel 4 with modern mode. I set it to Ch 4, tried both diode and tube rectifier, and used 4 6L6 mode. The other guitarist thought it didn't sound as "nasty" as other Dual Rec's he's heard...so I decided to do some research. The Dual Rec has, I believe, 5 12ax7's and 4 6L6's. The Road King II has a total of 6 12ax7's and can do 4 6L6's. I read the entire manual, and it says that if you bypass the effects loop system, it takes two 12ax7's completely out of the circuit....I talked to Mesa and was told that one of them is for reverb. Is the other one for the effects loop? Or is it running all the time? Does it have anything to do with the solo function? Basically, my question is: are there particular settings on Channel 4 that will *exactly* match the Dual Rectifier, or are there subtle differences? Sorry for being long-winded, and thanks for any help...