Denon PMA-780D (1987)
The PMA-780D tends to slip through the cracks of online catalogs. One Russian forum poster called it a "lost" model. It belongs with the PMA-580D, PMA-880D, and PMA-890D, Denon's late-1980s Japanese-market integrated amplifiers with multibit DACs on board. According to period sources, it was a completely new type of integrated amplifier: a conventional stereo amp with a built-in digital multi-interface circuit and D/A converter. It could take digital signals directly from CD players, DAT machines, and DBS (PCM satellite) broadcasts.
The digital section used what Denon called a "W Super Linear Converter" - a double super linear converter circuit with independent left and right D/A converters fed by a high-precision digital filter. The interface automatically identified and locked onto the sampling frequency of the incoming signal. Inside, the digital module (DAC) is mounted vertically. The input switcher board sits directly along the rear wall on the connectors themselves, a layout one owner described as "not bad." The power amp section used a super non-feedback design with a pair of MT-200 case output transistors, plus a "pure dynamic power" supply built around a hefty transformer. No optocouplers are visible on the boards. That leaves open whether this is a Japanese-only Class AB design or a shared "Optical Class A" topology, and the documentation doesn't settle it.
Specs from the record: 110W per channel into 8 ohms (20Hz - 20kHz, both channels driven), 130W into 6 ohms, THD under 0.004%, frequency response 5Hz - 100kHz, S/N 105dB, damping factor 80, slew rate 350V/µs. Dimensions are 434×172×396mm and it weighs 15.6kg. The phono stage handles both MM (2.5mV/47k) and MC (0.2mV/100). One Japanese retailer lists the weight at 9800g, which conflicts with the 15.6kg figure from two other sources. The heavier figure is kept here since it's corroborated. A price of 90,000 Y appears in one source (currency not specified), with 216W (J) and 400W (Eu) power consumption figures that likely reflect Japanese and European market ratings respectively.
Owners describe the sound as transparent with very generous low-frequency headroom, and the build quality as "a beauty, no argument." That said, the record is thin: no service manuals or schematics are known to survive, and most of what's documented comes from a single Russian teardown thread and a Japanese spec sheet. The PMA-880D appears to be nearly identical — "1:1, except for the inscriptions," per one owner — so if you're hunting for a 780D, an 880D may be the same amp underneath.
- Power: 2×110W (8Ω, 20Hz–20kHz, both channels driven); 130W+130W (6Ω)
- THD: <0.004%
- Frequency response: 5Hz–100kHz (IHF)
- S/N: 105dB; Dynamic range: 96dB
- Damping factor: 80; Slew rate: 350V/µs
- Phono: MM 2.5mV/47k; MC 0.2mV/100
- Dimensions: 434×172×396mm; Weight: 15.6kg
- Digital inputs: 3 (CD, DAT, DBS), auto sampling frequency selection
eBay Listings
As an eBay Partner, we earn from qualifying purchases. This helps support our independent vintage technology research.
Related Models
- Denon DL-160 (1979)
- Denon PMA-717 (1984–86)
- Denon AU-310 (1975)
- Denon AU-340 (1978)
- Denon DA-401 (1975)
- Eico 3150 (1967)
- Fisher CUSTOM-ELECTRA-I (K-14/K-15) (1957)
- Fisher CUSTOM-ELECTRA IV (E33/E44) (1960)
- Akai AM-2400 (1978)
- Akai AM-2600 (1977)