Stereophile|March 2022
Stax, EAR, and Bob’s Devices

A month ago, I ran into my Russian neighbor in the hall. As usual, he asked me what I was reviewing. (Vladimir likes to come over and listen, then find fault with everything I play.) When I told Vlad I had Stax’s new top-of-the-line earspeaker, the SR-X9000, he lit up and exclaimed, “I need to hear it,” adding that he has been a lifelong Stax fanatic and owns at least five different models, “dating way back.” He told me he’d recently sold his SR-009 to buy the newer SR-009S, but he still has his ragged, 25-year-old Stax Omega “prototype,” which sounds “even better” than the 009S. I told him I’d never heard that model and suggested he bring it by so that we could compare it to Stax’s latest “best” headset. He frowned. “It’s hidden in my room. I do not use them much at the moment, and no they are not for sale.” He promised a picture instead. “They’re really heavy, made of solid brass—and gold plated!” When I asked what the Omega sounded like, he laughed. “That headphone is a dream, Herb! So open, rich, and beautiful sounding. The bass is full although not as punchy as one might hope.” I begged him to find his gold-plated Omega and let me try it.


Stax’s new, big, expensive SR-X9000 electrostatic headphone ($6200) presents recordings with a purity, tonal neutrality, rhythmic ease, and resolve that I have not previously experienced with headphones— ever, whether dynamic, planar-magnetic, or electrostatic. Not even with Stax’s own SR-009S. On each of my most-played recordings, the SR-X9000 avoided blur, fuzz, dragging feet, and what-was-that-lyric confusion. It left no veils unlifted.

Which does not mean that every audiophile will think the new Stax is the best headphone ever—nor that they would choose it as their one-and-only. Competition for Best Headphone is beyond fierce. I encourage everybody to audition all contenders before buying, even the ones you can’t afford.


According to my Russian friend, Stax developed the Omega as an experiment. Their goal was to increase the size of the SR-X’s metal-mesh electrodes. (Vlad said he still uses his SRX-IIIs.) Stax engineers soon realized that keeping multiple larger electrode meshes stable and in perfect alignment was difficult in mass production. Therefore, Vlad told me, “not many were made.”

Today, the technology is in place to manufacture a sturdy, stable, lightweight enclosure for Omega-sized mesh electrodes. The SR-X9000 is the proof.

According to the Stax website, Stax’s “major technology advancement is the ‘MILER-3’ (Multi-Layer-Elect-Rords) - a four-layer fixed electrode combining mesh electrodes and conventional etching electrodes crimped together by thermal diffusion bonding. … The SR-X9000 diaphragm is made of ultra-thin engineering film that is 20% larger than the previous flagship SR-009S.” According to the Woo website, the diaphragm mass has been reduced “to create a lightning-fast reaction speed and more extended high-frequency response.”

On the SR-X9000, the Omega’s heavy enclosure has been replaced by a lighter, machined-aluminum one: Now the entire well-fashioned, superbly finished, open-backed headphone weighs just 432gm.

SR-X9000 + LTA Z10e

Linear Tube Audio’s dramatically useful, natural-sounding Z10e integrated amplifier is specified to make 10Wpc into 8 ohm loudspeakers. From its front-panel headphone jack labeled “HI,” the Z10 generates sufficient power for the hard-to-drive, 60 ohm, 83dB/mW HiFiMan Susvara. Through the jack labeled “LO,” it makes enough voltage to drive my beloved 300 ohm, 99dB/mW ZMF Vérité closed-backs. These are major accomplishments considering that the Z10e sounds equally superb on every output and costs only $4900 ($5400 with MM phono preamp).

In my world, German viola da gamba player Hille Perl and her American husband, Lee Santana, are about as hip, goodlooking, and creative as people can be. Santana plays lute, theorbo, and baroque guitar. I’ve spent many a night bathing in the harmonics of their 2004 recording Marin Marais: Pour la Violle et le Théorbe (16/44.1, Deutsche Harmonia Mundi/ Qobuz). But it wasn’t until I played it with the SR-X9000 that the effects of microphones, mixing, and sound-doctoring became obvious. The new Stax opened up this recording, recovering all the gorgeous tone color while resolving all the sensuous bow-on-string detail.

When I played Stravinsky Conducts Histoire du Soldat Suite (LP, Columbia MS 7093) through the SR-X9000, this stunning recording’s dramatic soundstage stayed entirely inside my head. I was a little surprised by that, because the Audeze CRBN electrostatic headphones I auditioned in Gramophone Dreams #56 presented images that extended outside my head, sometimes as much as 18 in front of my face. Nevertheless, the soundspace the Stax generated was full and complete, perfectly mapped, and cram-packed with delectable detail.

I wish you could have heard “The Devil’s Dance” from the History du Soldat Suite with the Z10e powering the SRX9000; the echoing harmonics, the sound of drumhead skins, and an X-ray view of the timpani were on full display. Nothing was blurred or missing. Details behind details inside details. What a pleasure.

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