Mhm
Also, from what research I've been doing (am busy boy :O) the "precursor to the Holocaust was the T4 program, one which Hitler did sign off on but later rescinded due to the public's negative response.
Additionally, before mid 1941 the "solution" was the removal of Jewish peoples from the state and controlled territories. I think it's a letter from Goering to Heydrich which serves as the only document signing off on the "final solution". Hitler's name is never mentioned.
Another thing to consider is by the end of 1942 Hitler was practically in hiding (he gave 8 speeches between 1943-1945 but 6 in 1942 alone), even if (hypothetically) he didn't sign off on the Holocaust but became aware of it, what was he to do? He was fighting a war on two fronts by this point. It would be one of those "We'll deal with them later" things.
Of course I'm very biased and strongly playing Devil's advocate, I just find it a fascinating possibility. I wonder how the public's opinion would change if a letter came out along the lines of "We're enacting the final solution, The Fuhrer must never know".