Marantz PM-64 (1984)
The Marantz PM-64 is a stereo integrated (pre-main) amplifier released in 1984 at ¥74,000. It was a digital-ready design that inherited the "digital support concept" of the larger PM-84. Its main feature was Marantz's AVSS (Auto Voltage Shift Supply), which shifted the output supply voltage according to the power demanded. The output stage ran at the most suitable voltage from small signals up to maximum output. The amp delivered 100W + 100W into 8 ohms (20 Hz-20 kHz) and stayed stable into difficult low-impedance loads. It kept its power even when speaker impedance momentarily dipped to very low values.
The "direct" switch was a notable feature for the era. It bypassed the tone amplifier and subsonic filter entirely and fed a digital source (CD player) straight to the power amplifier section through the shortest possible signal path. Both MM and MC phono inputs were provided for analog playback. The MM stage accepted up to 140mV and the MC stage up to 14mV. Rated distortion was low at 0.015% (20 Hz-20 kHz, 8 ohms), with a damping factor of 100. Optional side wood panels (WPM-64) were sold separately for ¥4,000.
The record on this model is thin. No period reviews from major English-language publications have surfaced in the archive's sources. Production dates beyond the 1984 release are unconfirmed. One database lists the production span as 1985-90, which conflicts with the release year and should be treated cautiously. A later PM-64 II / MKII variant existed. A PM-64AV version added video switching (9 audio and 4 video inputs) with CDV compatibility, but its internal specifications are undocumented. Owner reports on forums mention the amplifier running hot and a known failure mode of one channel producing no output. Bias adjustment and cold solder joints are cited as common culprits. Serviced units do appear on the secondhand market.
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