A Bryston 4B NPB solid-state stereo power amplifier, serial number 441860.

This is a class-AB2 amp that is housed in a solid metal casing. The front panel is composed of two 1/8-inch sheets of aluminum. The unit is rack-mountable and it has a chassis construction that allows it to run cool with the use of heat skink fins. 

Key features include:

• Output power: 250W continuous into 8 ohms, 400Wpc rms continuous into 4 ohms, 800W continuous into 8 ohms in bridged mode
• Frequency response: 1Hz–100kHz, ±3dB for 1W output.
• Total harmonic distortion: Less than 0.01% maximum
• Slew rate: 60 Volts / microsecond
• Current delivery: 16A continuous, 48A peak, per channel
• S/N Ratio: hum and noise, 108dB below rated output, 90dB IHF
• Serial number: 441860

The unit exhibits some signs of wear and tear on the top panel. There are screw holes on the front panel ears that make this unit rack mountable. This unit is missing one of its rubber feet, three of which present visible signs of wear likely due to age. 

The 4b was introduced by Bryston in 1976, since then they have been putting out reliable gear for audiophiles and touring musicians.

Condition Notes: this item has note been tested for operation.