Audiophiles have long admired electrostatic headphones for their uber-transparency, but they're all pretty expensive. Ah, but then Massdrop worked its magic on the $1,000 Koss ESP-950, rechristened it as the Massdrop x Koss ESP/95X, and slashed the price to $500! The sound is so pure, the ESP/95X will be a revelation to anyone who never heard an electrostatic headphone before.
It's a full-size, over-the-ear headphone system that includes a dedicated amp, the E/90X. The 'phones velour earpads are slightly scratchy to the touch, but overall comfort is superb, even when I'm wearing my glasses. The headphones permanently attached cable is 47 inches long, but you also get a 72-inch extension cable.
It's an open-back design so it doesn't isolate the wearer from external noise, and the ESP/95X's sound can be heard by anyone nearby.
The E/90X amp's connectivity options are limited to a Koss proprietary headphone jack, and two stereo analog inputs: a front-panel-mounted 3.5mm input, while on the back of the amp are deeply recessed RCA inputs that won't accept RCA plugs with thick connector barrels (the included RCA cables worked fine). The E/90X doesn't have digital inputs.
The front panel's volume control knob is split into separate left and right channel controls, and that's fine, but nearly every time I changed the volume I had to double-check to make sure the left and right channels were balanced. The amp is pretty small -- it measures just 2.6 by 4.3 by 6.1 inches.
The headphone and amp are mostly made of plastic, they don't have the solid feel or look of high-end designs, but the system is sold with the Koss lifetime warranty.
Listening to the ESP/95X Electrostatic System
The ESP/95X is most definitely a high-resolution headphone, but it doesn't mercilessly reveal harshness in recordings; the sound is on the warm side of neutral. Treble detail is there but never overemphasized, so pop phenom Billie Eilish's Don't Smile At Me album's aggressively compressed and processed sound was a pleasure to listen to. The ESP/95X made it so.
Over the ESP/95X, Mac Quayle's synth-driven score for the TV series Mr. Robot abounds with textures and deep bass tremors that lurk under soaring keyboard flourishes. Donning a set of Audeze LCD2 Classic planar magnetic headphones ($799) the music was less clear and spacious. The ESP/95X is more see-through transparent; the LCD2 Classic counters with superior dynamic punch, deeper bass and airier treble sparkle, but it's also a heavier, less comfortable headphone. Still, the LCD-2C has one decisive advantage: it can be plugged into any standard headphone jack, while the ESP/95X must be used with its E/90X amp (or an amp designed to power electrostatic headphones).
With well-recorded music, the ESP/95X will make you sit up and take notice. I loved Bela Fleck and Abigail Washburn's self-titled album of spirited bluegrass music. Both musicians play banjo, and their weaving lines are a delight. Washburn's vocals are free of processing and sound utterly natural.
The sound is addicting; once you get used to it other headphones will start to sound opaque and closed-in. The ESP/95X's light weight and extraordinary comfort will tip the balance for a lot of high-end shoppers -- you can wear these headphones for hours without fatigue. Best of all, the Massdrop x Koss ESP/95X is considerably more attainable than other electrostatics, so here's hoping more people can finally hear what they've been missing.