The horror, the horror. Basically this is the final Erno Borbely design. It is a current mode phono stage, where the cartridge looks into close to zero impedance. First stage with parallel J40/K170, and a power stage to drive the passive RIAA. Then a 40dB gain stage with power stage to drive the output.
It can be configured many different ways:
No feedback first stage, with input R of about 4 ohms for higher R moving coils
Feedback first stage which reduces input R to tiny value for low R moving coils.
Can be run single ended or balanced input, and single ended or balanced output.
I've set it up as a no-feedback version, fully balanced IO. There is a bal2unbal board which I currently have not wired in.
Shunt regulator for each board, layout by moi.
Dual power supply, each with dual bridge rectifier and lots of smoothing cap.