This AVA Super Pas Three is in very nice condition and was checked out here and repaired recently as the seller claims.
The vertical board is the line output buffer section, unity gain solid state buffer circuits isolating the tube line stage from real world loads. This unloads the tubes, improving their linearity, and allows the preamp to drive low impedance amplifier input impedance loads and long interconnect cable runs. The unit does have our vacuum tube phono section and optional jack set.
I would ask $595 for one this nice if I had one here.
Frank Van Alstine