STAX, the Japanese pioneer of electrostatic headphone technology and now part of Edifier, has unveiled the $2,890 SR-009D, the newest evolution of its legendary SR-009 electrostatic headphone platform. Building on the acclaimed SR-009 and SR-009S models, the new flagship earspeaker arrives in response to continued demand from audiophiles who still view the SR-009 line as a reference point for ultra-high-end headphone listening.
The electrostatic headphone category has also expanded significantly during the Head-Fi revolution, with strong alternatives emerging from brands such as Audeze and Dan Clark Audio. None of these systems are inexpensive, and all require a dedicated electrostatic energizer or compatible amplifier to operate properly. But the appeal is obvious: when done right, electrostatic headphones can deliver a level of speed, detail, and transparency that dynamic and planar designs struggle to match. And despite the growing competition, STAX remains part of every serious conversation about the category.
What Are Electrostatic Headphones?
Electrostatic headphones use a driver design similar to electrostatic loudspeakers, but scaled down for personal listening. Instead of a conventional dynamic driver or planar magnetic diaphragm, electrostatic headphones rely on an ultra thin membrane suspended between two perforated metal plates known as stators.
The diaphragm carries a constant electrical charge thanks to a conductive coating. When an audio signal is applied to the stators, an electrostatic field is created that pulls and pushes the diaphragm back and forth. This movement moves air and produces sound. Because the diaphragm is extremely light and tightly controlled, electrostatic drivers are known for exceptional speed, very low distortion, and a level of detail that many listeners consider reference grade.
There is a catch. Electrostatic headphones cannot be powered from a typical headphone jack. They require a dedicated high voltage amplifier often referred to as an energizer. One example is the STAX SRM-400S electrostatic driver unit designed to power compatible STAX headphones. This additional hardware makes electrostatic systems more expensive and less portable than most dynamic or planar magnetic alternatives.
There is far more to the technology than this short explanation, but the basics are simple: electrostatic headphones trade convenience and cost for speed, accuracy, and transparency.
Pro Tip: STAX refers to its electrostatic headphones as “Earspeakers.”
What’s New in the STAX SR-009D Electrostatic Headphones
The SR-009D brings several updates designed to improve usability, durability, and long-term comfort while preserving the electrostatic technology that made the original SR-009 a benchmark for high-end headphone performance. STAX has focused on refining key elements of the design rather than reinventing the platform, keeping the signature speed and transparency of the SR-009 series while aligning the new model with the company’s current lineup.
MLER (Multi Layer Electrodes): Both the SR-009 and SR-009D utilize STAX’s MLER (Multi Layer Electrodes) technology, which employs photo etched metal plates bonded at the atomic level. First introduced with the SR-009, the MLER design contributed to the headphone’s exceptional speed and “see through” clarity that quickly made it a reference point for electrostatic performance. The SR-009D retains the core MLER architecture but introduces refinements to the stator design. Rather than using the gold plated electrodes featured in the 2018 SR-009S, the new model returns to a refined version of the original SR-009 stainless steel plates, preserving the classic lightning fast SR-009 sound signature.
Detachable Cable: One practical improvement is the move to a detachable cable. The original SR-009 used a fixed cable, meaning damage or wear could require an expensive service repair. The SR-009D replaces this with a detachable cable system, providing easier replacement and greater flexibility for long term ownership.
Build and Comfort: The housing has also been redesigned to reduce overall weight. The original SR-009 used a heavy all aluminum frame, which contributed to its substantial feel during extended listening sessions. The SR-009D incorporates an injection molded unit case that significantly reduces weight to approximately 452 grams without the cable, improving long term comfort without sacrificing structural rigidity.
Sound Profile: STAX has also refined the tuning. The SR-009D smooths the midrange compared with the original SR-009, aiming for a slightly more balanced presentation while maintaining the speed, detail, and transparency that define the SR-009 platform.
Earpad Materials: Comfort is further enhanced with genuine sheepskin leather earpads designed to provide a secure fit and a more luxurious feel during extended listening sessions.
Headband: Instead of the friction slider used on the original SR-009, the SR-009D adopts a 10 step click adjustment mechanism for the headband. This provides a more precise and secure fit while improving long term durability and ease of adjustment.
Aluminium Carrying Case: The SR-009D also ships with a dedicated aluminum carrying case designed to protect the headphones during storage or transport. The lightweight but durable case helps shield the headphones from impacts, dust, moisture, heat, and general wear, supporting long term preservation of the system.
“The SR-009 has always held a special place in the hearts of our customers and in the history of STAX,” said Douglas Ip, Sales & Marketing Head, STAX Limited. “With the SR-009D, we are thrilled to bring back that legendary sound, updated with the features that our customers have long asked for. It is the perfect gateway to the world of high-end electrostatic audio, offering an unmatched listening experience at a much more accessible price point.”
Comparison
| SR-009D (2025) | SR-009S (2018) | SR-009 (2011) | |
| Product Type | Over-ear Headphones | Over-ear Headphones | Over-ear Headphones |
| Price | $2,890 | $4,545 | $5,250 |
| Headphone Type | Push-pull electrostatic sound element. Open-back type enclosure. Large round shape | Push-Pull Open Back Circular Electrostatic Headphone | Push-pull electrostatic circular sound element. Open-air type enclosure |
| Frequency Response | 5 – 42,000Hz | 5 – 42,000Hz | 5 – 42,000Hz |
| Capacitance | 110pF (including cable) | 110pF (including cable) | 110pF (including cable) |
| Impedance | 145 kΩ (including cable, at 10kHz) | 145 kΩ (including cable, at 10kHz) | 145 kΩ (including cable at 10kHz) |
| Sound pressure sensitivity | 101dB / 100V r.m.s. 1 kHz | 101dB / 100V r.m.s. 1 kHz | 101dB / input 100Vr.m.s / 1kHz |
| Max sound pressure level | 118dB / 400Hz | 118dB / 400Hz | 118dB / 400Hz |
| Bias voltage | 580V DC | 580V DC | 580V DC |
| Earpad | Genuine sheep leather, artificial leather (surrounding portion) | Genuine Lamb Leather (direct skin contact), high-quality synthetic leather (surrounding portion) | Genuine leather (Lamb) |
| Cable | OFC parallel 6-strand, low-capacity wide cable 2.5m | Silver-coated 6N (99.9999%) OFC parallel 6-strand, low-capacity special wide cable, 2.5m full length | Silver-plated 6N (99.99999%) OFC low-capacity wide cable 2.5m |
| Weight | 580g, (452g without cable) 1.25 lbs (1 lbs without cable) | 596g, (454g without cable) 1.3 lbs (1 lbs without cable) | 596g, (454g without cable) 1.3 lbs (1 lbs without cable) |
The Bottom Line
The SR-009D keeps STAX firmly planted at the top of the electrostatic headphone conversation, but it does something the original SR-009 never really attempted: it lowers the barrier to entry. By dropping the price from roughly $4,500 for the previous flagship models to $2,890, STAX is making its most iconic electrostatic platform considerably more accessible to serious listeners who may have admired the 009 series from afar.
That doesn’t mean it’s suddenly a budget product. Electrostatic systems still require a dedicated energizer or compatible amplifier, which means the total investment for a complete setup can easily climb well past $5,000. But for audiophiles already exploring summit-level headphones, the SR-009D delivers the legendary speed, transparency, and scale of the 009 series at a significantly lower price than before.
And for those who want to step into the STAX ecosystem without committing to flagship territory, the company now offers more approachable options such as the SR-X1, which starts around $535. It’s still not cheap, but compared with the cost of most electrostatic systems, it’s a reminder that STAX is trying to widen the door into one of the most revealing ways to experience music through headphones.
Price & Availability
The SR-009D is available now directly through STAX, Authorized Dealers, and Distributors. North America Pricing is $2,890.
Note: The SR-009S is still available for $4,545 and the original SR-009 has been discontinued for some time.
Related Reading:
- Meet the STAX SR-007S—Electrostatic Tech So Next-Level, Your Old Headphones Are Jealous
- Stax SR-X1 Earspeaker Review: Can a $535 Electrostatic Headphone Convince the Naysayers?
- Stax SR-L700 MK2 Open-Back Electrostatic Earspeaker Headphone: Review
- Audeze CRBN2 Electrostatic Headphones Review: Is it Time to Sell Your Loudspeakers?
