VAC Valve Amplification Company PA-90b/PS-90b amp/power supply 4 chassis dual-mono pair

This amp is a four chassis dual-mono amplifier/power supply pair, two separate power supplies and two separate amplifier channels. They have eight of the older NOS style Svetlana EL34, known as Winged C nowadays. Those appear as near new. The front-end tubes are also NOS. The sound is excellent
Following from VAC owner manual:
Some of the features of your power amplifiers include: The maximally balanced push-pull circuitry, with push-pull conversion (phase inversion) occurring in the first stage, better exploits the inherent advantages of push-pull operation and allows improved performance of the driver stage. Modest loop negative feedback (8 dB) ensures better dynamics, gentle clipping, and superior overload recovery. Simple feedback arrangement avoids unnecessary multiplication of the order of distortion products. Completely hand wired in three dimensional space for the shortest possible lead lengths, allowing passive components to perform much nearer to the theoretical ideal. All chassis are machined 1/8 inch thick aluminum, creating an extraordinarily rigid nonmagnetic platform that is unusually resistant to vibrations that could mar the sound. Mechanical vibration from the power supply is completely isolated from the amplification circuitry due to the multiple chassis design. Energy storage is distributed among the chassis to place it nearer to the point of demand and dedicated to particular uses, ensuring superior isolation of the various stages. Output stage is based on the KT77 Beam Power tube or the EL34/6CA7 Power Pentode operated in Class A at 54 milliamperes idle current per tube. Output stage may be operated in partial-triode (ultra-linear) or full triode mode, selected via a single switch. Impedance matching taps are provided for 2, 4, and 8 ohms.