Harman Kardon PM645 (1988–1992)

The Harman Kardon PM645 is a solid-state integrated amplifier from the late 1980s, representing the final and most powerful version of the PM series that began with the PM640. It was positioned directly below the PM655 in the lineup. The amplifier is built around a "High Current / High Voltage" design philosophy, a hallmark of this era of Harman Kardon — the high-current ICs (Sanyo STK) used inside were typical of the period's approach to driving difficult speaker loads.

The record on the PM645 is decent on specifications but thin on reception. Contemporary coverage of the related PM665 Vxi appeared in HiFi-Stereo (February 1988, p.121), but no independent reviews of the PM645 itself were located in the research. What is well documented, and corroborated across multiple independent sources, is the basic performance envelope: 100 watts per channel into 8 ohms, a frequency response rated from 0.5Hz to 200kHz (+0/-3dB), and a signal-to-noise ratio of 100dB on high-level inputs. The unit offers bass and treble tone controls (±10dB at 50Hz and 20kHz respectively) and supports speaker loads of 4 to 8 ohms. Inputs cover phono MM, tuner, CD, and two tape loops, with tape outputs, pre-out, speaker, and headphone connections on the output side. Physical dimensions are 440 × 121 × 371mm, and it weighs 10.8kg.

A note on variants: a version letter "Vxi" (PM645 Vxi) exists for the European market, and some specifications — including the 130-watt-into-4-ohm figure and the dual-transformer power supply detail — are documented specifically under that variant, not the plain PM645. The two should not be conflated. No original price, damping factor, or input sensitivity figures for the plain PM645 have surfaced in the accessible record.

Power output: 100W/ch into 8Ω (20Hz–20kHz)
Frequency response: 0.5Hz–200kHz (+0/-3dB)
S/N ratio: 100dB (high level)
Inputs: Phono MM, Tuner, CD, Tape 1, Tape 2
Outputs: Tape 1, Tape 2, Pre out, Speaker, Headphone
Dimensions: 440 × 121 × 371mm; 10.8kg

Production years are generally cited as 1988–1992, though this appears to be an approximation rather than a precisely documented date range. Beyond its listed specifications, little else — no service notes, no collector pricing, no common failure reports — has been recorded about the PM645.