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Pass Labs debut INT-60 integrated, headphone amp at CES 2015

  • CES_2015Rugged glory. My direct experience with Pass Labs amplifiers sums to zero but Nelson Pass has a well-cemented reputation as one of the world’s finest amplifier designes. He’s the amp designer’s amp designer – that’s how Hugh Dean of Melbourne’s NASKA/Aspen tells it. Zu Audio’s Sean Casey is also a BIG fan.

    Michael Lavorgna runs the most excellent AudioStream website and is also now a staff writer for Stereophile. Over dinner on Thursday night his enthusiasm spilled big for the Pass Labs INT-60 integrated amplifier, more than enough to have me lock in a visit to the Pass Labs room on the 34th floor of the Venetian Hotel the following morning.

    Of course, Pass himself wasn’t in attendance but Lavorgna might be interested in the new INT-60 integrated that doubles down on his own amplifier’s 30wpc…but without doubling up on price. The INT-30 sells for US$6000 whilst its newer sibling will retail for US$9000.


    To spell it out in more simplistic terms: the INT-60 will drive 60 Class A watts into an 8 Ohm load. And simplicity is Pass’ thing; the INT-60 loads in only two gain stages – affording “improved gain management” according to representative/mainstayer Wayne Colburn – whilst borrowing the output stage and power supply from the Point 8 designs. The circuit is fully balanced.

    Cooling fins loom large on each side and out back we note 4 x line-level inputs (balanced and single ended), pre-amplifier outputs, a line-level output and Furutech loudspeaker binding posts.

    Much marketing noise is also being made of the front panel’s glowing meter. If there’s one thing audiophiles love it’s a glowing meter. An no, I’m not being sarcastic.

    The INT-60 is assembled entirely in California and will be available “in the next couple of months”, according to Colburn. For those with more cash at their disposal or those with greater power needs (or both), the similarly new INT-250 will sell for US$12000.

    Jam Somasundram of Pass Labs.

    Meet Jam Somasundram. He’s the engineering brains behind Pass Labs’ forthcoming headphone amplifier. It’s so fresh it doesn’t have a name yet and the balanced inputs on the rear panel are being ditched for the retail version proper. Somasundram says a balanced model will appear down. For the time being this headphone amplifier’s circuit is strictly single-ended.

    For the time being Pass Labs’ new box is being referred to simply (there’s that word again) as “Headphone Amplifier”. And keeping true to house principles the circuit is all Class A and fully discrete, which also applies to the voltage regulators. Somasundram describes global feedback as “low”. Bringing the juice is a custom designed toroidal transformer wrapped in Faraday shield, which reportedly prevents high frequency noise from polluting the circuit.

    Somasundram voiced his design with Audeze LCD-X and Sennheiser HD800 and whilst power specifications proper are still to be confirmed 24V rails are likely to ensure compatibility with headphones from 20 – 600 Ohm headphones. The casework is typically battleship-like and a variable output means a pre-amplifier role is also possible.

    The Pass Labs headphone amplifier is expected to sell for US$3500.

    Further information: Pass Labs

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    Written by John

    John currently lives in Berlin where he creates videos and podcasts for Darko.Audio. He has previously contributed to 6moons, TONEAudio, AudioStream and Stereophile.

    Darko.Audio is a member of EISA.

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