Marantz PM-KI Ruby Ken Ishiwata Signature Reference Integrated Amplifier
Marantz has been designing and making amplifiers for more than 65 years, and for 40 of those the products have reflected expertise of Ken Ishiwata. Now, to mark his four decades with the company, the PM-KI Ruby amplifier has been developed and tuned by a highly experienced engineering team led by KI himself. . Features a fully discrete two-stage design with separate power supplies for the pre-amplifier and power amp — plus, a moving coil/moving magnet phono stage complete with Marantz Musical Premium Phono EQ circuit and Marantz HDAM technology for signal purity and exceptional audio quality. PM-KI Ruby is built on a vibration-resistant double layer chassis with thick aluminum panes for rigidity and features a laser-engraved Ken Ishiwata signature to commemorate his legacy.

Key Features
Engineered and extensively tuned legendary Marantz sound master Ken Ishiwata and his team, drawing on more than 65 years of Marantz amplifier design knowledge
Marantz high-resolution preamplifier stage with proprietary HDAM technology
Switching power amplifier design derived from flagship PM-10 amplifier
Generous output: 100W + 100W (into 8ohm), 200W + 200W (4ohm)
Fully-discrete, two-stage design for signal purity, with separate power supplies for preamp and power amplifier sections to reduce interference
Toroidal transformer dedicated to preamp for clarity and powerful sound
Current feedback design with newly-developed wide-range circuitry
HDAM® SA3 circuitry for clean signal and optimal dynamics
MM/MC Phono input with new discrete Marantz Musical Premium Phono EQ circuit
Thick nickel-plated copper independent input terminals for CD and Phono, plus Marantz-original high-quality/high-purity copper-plated speaker terminals
Linear volume control with new electric volume system
High-quality construction with double-layer chassis, 5mm thick aluminum top lid, solid aluminum front and copper-plated chassis
High-grade, carefully selected audio parts: ultra-low leak current Schottky diodes, low noise complementary transistors, high-grade resistors, newly developed custom electrolytic capacitors, audio grade film capacitors and mica capacitors.
Laser-engraved Ken Ishiwata signature and Ruby motif, marking Ishiwata’s 40-year Marantz legacy


Celebrating 40 Years of Passion
Designed to celebrate the 40-year anniversary of legendary Marantz sound master, Ken Ishiwata, PM-KI Ruby features pinnacle performance that’s synonymous with Marantz excellence. Complete with thoughtful engineering, painstaking tuning and extensive listening sessions, PM-KI Ruby achieves the elevated output worthy of its name. Elegantly shows Ishiwata’s laser-engraved signature to commemorate the design and heightened listening experience that honors the decades-long partnership between him and Marantz.

Extensive Sound Tuning
Led by Ken Ishiwata’s extensive, meticulous approach to tuning, the larger Marantz engineering team applied more than 65 years of experience and HiFi knowledge to create PM-KI Ruby, resulting in a final product that is a testament to Ken Ishiwata and the Marantz legacy.
Marantz HDAM Technology
Marantz developed its own discrete circuit boards called Hyper-Dynamic Amplifier Modules, or HDAMs, to replace the chip-based amps used elsewhere. Using discrete surface mount components with short mirror-image left and right signal paths, HDAMs outperform the regular integrated Op-amps dramatically in Slew Rate and noise level. The result is much more dynamic, accurate and detailed sound. Over the years, Marantz has developed different HDAMs to fit the particular requirements of players and amplifiers. The PM-KI Ruby uses the latest high-grade SA3 version. Combined with optimized circuit design layout and carefully selected components, the PM-KI Ruby provides exceptional sound quality and performance.

Marantz Musical Premium Phono EQ
Designed to deliver optimal sound quality by simplifying the signal path, the Marantz Musical Premium Phono EQ stage in the PM-KI-Ruby amplifier can be used with both moving magnet and low-output moving coil cartridges, thanks to a built-in MC head amplifier. Distortion is reduced by using two-stage amplification in the phono stage, and Marantz HDAMs are combined with JFETs (junction gate field effect transistors) in the input stage, giving high input impedance. The exclusion of coupling capacitors further simplifies the design, reducing signal distortion and enhances signal purity.

High Quality Volume Control
Newly developed electric volume control uses the latest volume control IC to realize better channel separation, dynamic range and distortion-reduction, while retaining the operational feel of an analog volume control device. The amplifier employs new Marantz-designed electric volume control for high linearity and best-in-class channel separation.
Current Feedback Amplifier
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