Massdrop x Sennheiser HD 6XX Headphones

If you know audio gear, you know the Sennheiser HD 650. The company’s flagship from 2003 to 2009, this open-back headphone has shown serious staying power. Praised for its richly detailed, effortlessly enjoyable sound, it remains one of the most talked-about products on Head-Fi today—and is still widely considered among the best headphones under $1,000. So when we teamed up with Sennheiser on its first-ever community-driven design partnership, the HD 650 was a natural place to start. A new revision of the popular all-rounder, the Massdrop x Sennheiser HD 6XX has that same great sound plus a few updates, and a price that makes it even easier to love.

Crafted with the modern audiophile in mind, the HD 6XX replaces the HD 650’s gray colorway with something darker and more dramatic: a deep midnight blue. The silver nameplates have been swapped for black plates with contrasting silver text—and the Massdrop logo is silk-screened on the inside of the headband, just above the right cup, with the serial number located just above the left cup. Based on feedback from the community, this iteration has also been updated with a detachable 6-foot cable (compared to the original’s 10-foot cable) and a ⅛-inch plug, which is more versatile for everyday laptop, phone, and DAP use than the standard ¼-inch plug. Of course, the HD 6XX comes with a ¼-inch adapter for those who want it.

Good news for fans of the HD 650: In this revision, the driver structure and sound signature haven’t changed a bit. You’ll get the same smooth, laid-back presentation, with a balanced midrange and natural-sounding bass. The HD 650 is considered more refined and better damped than its predecessor, the HD 600, with less energy in the upper midrange (which some listeners may find less fatiguing) and an overall balance that’s a bit warmer and bassier. Its neutral response provides a pleasant listening experience with any musical genre from a range of sources. Plus, it responds well to improved sources and amplification, and headphone amplifiers of any output impedance could potentially make a good match.

Because the HD 6XX’s open-back design won’t isolate you from outside noise or prevent sound from being heard by those nearby, it may be best-suited for quieter home and office environments. Like all headphones in Sennheiser’s HD 600 line, this new model can be disassembled by hand to its component parts, all of which can be easily replaced. Many of its parts are interchangeable with others in the series, and owners of the HD 6XX can benefit from the rich aftermarket and brain trust of modifications and gear matching—along with excellent long-term support from Sennheiser itself.

In 2011, audio engineer NwAvGuy published a blog post titled “O2 Headphone Amp,” in which he outlined his philosophy on defining sound quality and detailed his ideal audiophile circuit design. Our version of NwAvGuy's famous O2 amplifier, the Objective 2 Desktop Edition features updates based on feedback from the community. It’s an ideal baseline reference amplifier, capable of powering everything from IEMs to HD 800s with linear ease. We recommend the medium gain version if you plan to primarily use this amp with IEMs. If you don't plan to use IEMs, if your headphone has a 300-ohm or higher impedance, or if your source is weak (less than 2V output), opt for the standard gain version to ensure enough power.

Want to upgrade your HD 6XX with a premium feel and enhanced sound signature? These earpads (available in four styles) provide a breathable, cushioned, enveloped feel for hours of fatigue-free listening. The velour pads feature soft, tight-knit velour covers that are stitched at the seams for security and a good seal; the supple sheepskin pads deliver a tight soundstage and truer sound, thanks to the increased absorption of more early reflections before sound enters the ear; the fenestrated sheepskin pads are similar to the sheepskin pads, with perforations for a more breathable design; finally, the hybrid velour pads combine a sheepskin outer ring with velour on the face for the best of both worlds.

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