MASS-Kobo Model 475 reference headphone amplifier, hero product shot
MASS-Kobo

MASS-Kobo Model 475

Sale price$1,900.00

The MASS-Kobo Model 475 brings M. Masuda's fully balanced amplifier engineering to a portable battery-powered format, a compact, high-performance headphone amplifier that runs on four AA batteries or USB-C power delivery, with the same attention to signal quality that defines the desktop lineup.

Type and Technology

Fully balanced portable headphone amplifier, solid-state. Single 4.4mm Pentaconn input with a mode switch to accept unbalanced sources via a conversion cable. Balanced 4.4mm TRRS and unbalanced 3.5mm TRS outputs. Internal gain switch (Hi/Lo) for accommodating both sensitive balanced armature IEMs and inefficient full-size planar headphones. Battery powered (4x AA alkaline or rechargeable) or USB-C power delivery. Made to order in Japan.

Sound Character

Clean, composed, and remarkably low-noise for a battery-powered design. The 475 delivers the MASS-Kobo character in a portable package, a transparent and controlled presentation that lets the headphone and source speak without interference, with a noise floor low enough to pair comfortably with sensitive IEMs on the Lo gain setting.

Build and Finish

Compact and solid construction at 97 x 132 x 40mm. Battery operation provides approximately 4 hours of use from alkaline AA cells (varies by battery condition and type). USB-C port for external power delivery only, not for charging. The external power supply input has been updated from Micro-USB to USB-C.

Best For

Audiophiles who want MASS-Kobo's amplifier quality in a portable format, for travel, desktop use with a DAP, or anyone who wants an analog gain stage between a balanced source and their headphones or IEMs.

What's in the Box

  • MASS-Kobo Model 475 portable headphone amplifier

Please note: This is a made-to-order product. Production time is approximately 1 to 4 months from order. No cancellations are accepted after an order is placed. Custom duties are the responsibility of the customer. Balanced output does not support unbalanced headphones directly, a conversion cable is required.

Specifications

Specification Value
Type Fully balanced portable headphone amplifier, solid-state
Input 4.4mm TRRS x1 (balanced or unbalanced via conversion cable)
Outputs 4.4mm TRRS (balanced), 3.5mm TRS (unbalanced)
Gain switch Hi / Lo (internal)
Max output without distortion 165mW balanced, 45mW unbalanced (32 ohms, 1kHz, THD+N 0.5%)
Frequency response 20 Hz - 20 kHz (-1 dB)
Noise floor Less than 40μV (min volume, 32 ohms loaded)
Power 4x AA battery (approx. 4 hours), or USB-C power delivery (5V)
Dimensions (W x D x H) 97 x 132 x 40 mm
Weight 440g (with batteries) / 382g (without batteries)

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