Hi everyone,
I am in the process of building a mesa boogie Dual Rectifier Solo head and I had a Question. At the top of the circuit for this schematic are a few letters. Are those where it connects to the power amp or effects loop or something? The rest of the schematics for this amp are here. Thanks in advance for all your help

The letters at the top show what voltage to connect certain preamp stages to. "That Pink Queen" seems to the guy to talk to about tube amps, I'm sure he knows more about them than I do, but if I were you I wouldn't attempt this if you don't know everything about what you're doing. As you've probably read everywhere before, voltages in tube amps can kill blah blah blah. If you know nothing about tube amplifiers or electronics in general you will be much better off buying a kit. Of course I could have you all wrong and you may know a lot about electronics but, having built Mesa-styled preamps before, I can say that they hum and squeak a lot if you layout the wires wrong. I'm sure someone else said that earlier today too.
Despite how it seems those schematics aren't a cheap way to get a 100W tube amp. The parts alone may only come to 1/10th of the price, but if this is your first build it won't work like a real Mesa should. Sorry to sound like an a*shole but if you don't have any experience you're better off with a kit.