By the way that is a balanced board.
I have no idea what it is going to cost.
that340 input chip is $6.40
opa445 if you want to run +/-20 are $11 each or $6.50 each in smt plus the brown dog adapter (2 are needed)
everything else is pretty cheap.
If you can get the singles fets, 4 fets fit
nicely into the socket in place of the that340. And there
are 2 different kinds of feedback one is supersymmetry.
Any update on this, Kevin?