Denon PMA-S10 (1995–1997)

Name: Denon PMA-S10
Brand: Denon

The Denon PMA-S10 started a family of integrated amplifiers for Denon in the mid-1990s. It ran through two revisions - the PMA-S10II (1997) and the PMA-S10III (2000) - before the line turned into the PMA-SA11. Denon positioned it as a high-end pre-main amplifier, and the original carried a retail price of ¥220,000 in 1996 (roughly $2,050 at the time). It weighs 15.2 kg. The design philosophy comes from Denon's flagship POA-S1 and PMA-S1 separates, aiming for a balance of delicacy and strength.

The core of the design is Denon's UHC-MOS (Ultra High Current MOS) output stage, used in a single push-pull configuration. Denon built UHC-MOS to answer the perceived current limitations of conventional MOSFETs. It supplies current equal to or better than bipolar transistors and keeps the MOSFET's sonic character. The original PMA-S10 was rated at 100W + 100W into 4Ω and 50W + 50W into 8Ω (20 Hz - 20 kHz), with a THD figure of 0.07% at 1 kHz. A cascode bootstrap method gives the power stage an ideal load, and the source resistance - a common source of sound coloration - was eliminated entirely. The power supply uses a large transformer and block capacitor to support the UHC single push-pull circuit. The chassis is rigid copper-plated steel plate, with sintered alloy insulators fixed directly to it for vibration control. The phono stage handles both MM and MC cartridges, and a tone defeat switch removes the tone circuit from the signal path completely for straight playback.

The PMA-S10II debuted in February 1997 at ¥230,000. It was a substantial evolution, not a light refresh. It doubled the 8Ω output to 100W + 100W and pushed to 200W + 200W at 4Ω. The S10II uses a twin-monaural configuration with independent left and right power amplifier blocks, a six-block internal structure that separates circuits by signal level, and a 1.6 mm steel chassis. The power transformer has a low-flux-density magnetic circuit with an LC mount system to cut leakage flux, and separate windings for the voltage amplifier stage, phono equalizer, and control circuits. Parts also came over from the S1 series: a 40-step 4-channel volume control, large machined gold-plated pin jacks, OFC internal wiring, inert gas-filled relays, and a detachable AC cord. At 30 kg, it is a heavy amp. One Russian seller's listing described it as a "30kg welder with a soul." The S10II's sound has been described as "magnificent, epic, monumental."

The final version, the PMA-S10III (2000, ¥250,000), kept the S10II's basic configuration and added more material investment for sound quality. It uses the UHC-MOS with a peak current rating of 120A - three to ten times the current supply capability of conventional amplifiers. It also introduced a Schottky barrier diode in the rectifier circuit, claimed as a first for a mass-production amplifier's power supply. The S10III added a Precision Signal Ground circuit to reduce noise current inflow. Revisions to the volume, tone, and power amplifier circuits improved the upper frequency limit in actual use to 100 kHz. At 28 kg, it is slightly lighter than the S10II. One note in the record says the S10III and the later PMA-SA11 are, in essence, the same amplifier.

Documentation on this family is uneven. The original S10's spec sheet is thinner than the II and III versions - no tone control values, frequency characteristic, or power outlet specs are recorded for it. The S10III's listing on audio-database.com shows a RIAA deviation of ±0.5 dB for MM, which conflicts with the S10II's ±0.3 dB despite the shared phono equalizer design. The S10III figure is retained as listed. Common issues reported by owners include the S10II running hot (likely normal bias behavior, per a HifiForum.nl discussion) and a humming complaint on the MkII.

The S10 family has held its value well on the secondhand market. Current asking prices on Russian classifieds range from roughly 68,000 to 85,000 rubles for the original S10, around 124,000-127,000 rubles for the S10II, and 129,000-169,000 rubles for the S10III. A serviced S10II listed on US Audio Mart in late 2025 was asking $1,425.