Mesa IIc+ coming together

I would avoid putting all of the circuits on one colossal PCB. Mesa does this, and they are a royal PITA to service. Many amps end up getting disassembled and abandoned because servicing them is more than most people can handle. When one component fails and needs to be removed/replaced you end up having to disassemble/un-manufacture the entire amp just to change a through-hole component like a failed cathode bias resistor. That's a very bad design. Even worse, Mesa hard-wires their boards, so the board's circumference radiates dozens of wires, each of which has to be de-soldered to remove the board. The entire amp ends up being de-manufactured just to access the board. Once the board is fixed, it's another asspain to put it all back together. IMO you're far better off with a modular approach comprised of sub-boards rather than a single heavy duty board, as this relieves the burden on the tech when it comes time to service the amp. Obviously, Mesa doesn't care about this. I hate servicing my Mk IV -- it has through hole components that are stacked 3-high like pancakes.

Another thing to consider is quick disconnects. It makes no sense to permanently wire the board to the chassis without any consideration for how difficult it will be to service when the time comes. This is a major oversight in the designs that focus on large boards. If you insist on monolithic boards, do everyone a favor and populate them with ribbon cables that have quick disconnects. It's obvious that Mesa designs their amps with no consideration whatsoever for servicing them. When they eventually fail -- and ALL Mesas eventually do fail -- they aren't cost effective to fix because they are designed to minimize construction cost and to last just long enough to make it through warranty, and once that point is reached Mesa doesn't care about how hard they are to service. Do everyone a favor and don't follow a bad leader.