Nakamichi PA-50 (c. 1988–1991)

The Nakamichi PA-50 is a stereo power amplifier from the company's late-1980s separates push. The Vintage Knob calls it the "little sister" of the PA-100. It was the amplification half of a pairing with the CA-50 preamplifier, marketed together as a compact reference-grade system. Production dates are fuzzy. The Vintage Knob says it was introduced in 1988 and sold until 1990, while hifi-wikia lists it as 1989-1991. No original retail price has surfaced in any source.

The PA-50 is rated at 100W per channel into 8Ω (20Hz - 20kHz, 0.02% THD), with a signal-to-noise ratio of 100dB and input sensitivity of 1V. The Vintage Knob gives a wider frequency response of 1Hz - 100kHz (+0, −1dB). HiFi Engine is more conservative at 20Hz - 20kHz. Damping factor is listed at 100, input impedance at 30kΩ, and power consumption at 340W. It measures 435 x 135 x 420mm (WxHxD) and weighs 11kg.

Inside, it is a dual-mono design: two independent power supplies fed by a single large toroidal transformer, with two 18,000µF reservoir capacitors. The output stage uses large discrete power transistors on substantial heatsinks. A protection circuit engages relays in the event of DC offset or overheating. Two pairs of speaker outputs are provided. The record conflicts on inputs. HiFi Engine lists only a single RCA pair, while The Vintage Knob says the PA-50 has balanced XLR inputs alongside the standard RCAs. The Vintage Knob's treatment of the unit is more detailed, so the XLR inputs are plausible, but the discrepancy is unresolved.

The Vintage Knob describes the sound as transparent, detailed, and neutral, with strong dynamics and a spacious soundstage. It also notes the PA-50 runs extremely hot during operation and needs adequate ventilation. On the used market, the known failure points are age-related relay failure, which is a common technician fix, and output transistors that are no longer in production. The unit is also said to benefit from recapping after several decades of service.