Mass-Kobo Model 491

Mass-Kobo Model 491

Hand-built twin-balanced monoblock headphone amplifier from Japan

The Mass-Kobo Model 491 is the successor to the acclaimed Model 465 and embodies one of the most uncompromising manufacturing philosophies in headphone amplification: every unit is hand-built in Japan and personally tested and signed off by Mr. Masuda, the founder and designer of Mass-Kobo.

Rather than the conventional stereo circuit found in most headphone amps, the Model 491 uses a twin-balanced monoblock topology with four independent amplifier stages and two fully separate power supplies for the left and right channels — an architecture more commonly found in high-end loudspeaker power amplifiers than in a headphone amp. The result is an exceptionally low noise floor and channel separation capable of driving demanding, power-hungry planar magnetic headphones like the HiFiMAN Susvara to reference-level performance.

The Model 491 offers two balanced XLR inputs and two unbalanced RCA inputs, and covers virtually every common headphone connector with a 4-pin XLR, two 3-pin XLR L/R, balanced 4.4mm and unbalanced 1/4" TRS output. Construction uses lead-free solder throughout, and every unit ships in a rugged Pelican transport case.

As the successor to the Model 465, the Model 491 carries its monoblock concept into a more compact desktop chassis without compromising on noise floor, channel separation or output power. Because every unit is built to order, production numbers are inherently limited.

Technical Specifications