For those deeply invested in the Head-Fi community, very little needs to be said about STAX and its enormous contribution to the world of high-end headphones and the electrostatic category; the brand has been active since the 1970s and despite multiple ownership changes over the years, the company is still going strong. When its situation turned rather dire in 2011, it was acquired by Edifier which is based in China. Products like the STAX SR-X1 would never have come to market without that acquisition.
The new parent company has allowed STAX to do what it does best – innovate and create some of the best headphones currently available. That strategic decision has resulted in a steady flow of improvements to existing models and the creation of the new flagship, SR-X9000 which was recently introduced.
Having not had the opportunity yet to experience the $6,200 SR-X9000 and compare it to the category leading Audeze CRBN2 (see our full review), we really can’t say which one is superior – but that will happen in the near future.
And that doesn’t even include the additional cost of an energizer (electrostatic headphone amplifier) that one requires to actually drive them – which can add at least $1,500 to the cost of the entire package without a source device.
That reality has always been the knock against electrostatic headphones – it’s like taking the family to Disney for the day and that’s before the kids demand their overpriced Star Wars t-shirts and Disney Princess outfits.
It has been almost impossible to join the club for under $1,000; even the entry-level Koss models have been sold for $999 USD.
But then the strangest thing happened on the way to the In-N-Out Burger in Mission Viejo – the headphone industry started charging between $2,000 and $5,000 for a pair of dynamic or planar magnetic headphones.
Electrostatic headphones suddenly became…affordable?
When you stop choking on that double-double, understand that we agree that all of those price points are unrealistic for 95% of the market.
STAX, to its credit, has always had models within the range that were designed for those enthusiasts who had less to spend. This started with the original SR-1 and later SR-X models – and we can’t forget about the entry-level Lambda models.
Fast forward to 2025 and the STAX catalog includes the SR-003 MK II (read our review) IEM, SR-L300 Earspeaker ($455 USD) and the STAX SR-X1 that is our focus for $535 USD.
The SR-X1 feature trickle down technology from the SR-009S and SR-X9000.
Build Quality
The packaging is somewhat austere and opening the box revealed a pair of the SR-X1 headphones, supplied cable, and warranty card. Rather spartan to say the least but also the first hint that STAX only spent money where it matters – on the actual headphones.
Electrostatic headphones can be somewhat fragile and you will notice almost immediately that these are not very heavy; 234 grams compared to the more expensive STAX SR-009S that are 453 grams without the cables.
The overall aesthetic is a mix of black and silver with metal bands and polymer ear cups.
We did have one issue during the unboxing where both ear cups were detached from the headband and gimbals – they were not broken but the gimbals are a spring steel band with posts on either end that insert into the ear cups and it didn’t take a lot of force to dislodge them.
I had the same happen on another occasion when I bumped the gimbal on the headphone stand post. Luckily I caught the cup before it succumbed to gravity.
The spring steel gimbals attach at the center point to a post/box arrangement with 5 graduations on the post and a locking mechanism inside the box. This gives a total of 6 possible sizes (assuming same level on both sides). There is a slot cut on the inside of the boxes that mates to a post on the rod that prevents over-extension or compression.
The headband is a pair of spring steel bands covered in leather that connect to the upper side of the boxes. The cups are made of the same black polymer as the boxes and are a fairly simple design. The outer cup sports a tab at top that abuts the gimbal and prevents over rotation on the horizontal axis.
Opposite the tab is the oblong cable port with 3 pins visible inside and a notch cut that prevents cable insertion in reverse. The grill on the outside face is horizontal bars while the inner grill is an elongated honeycomb shape stretched vertically. The ear pads are leather with a wider portion at front and rear making the internal space a vertical oblong. I found this slightly odd as the pads do appear to obstruct a portion of the drivers.
Thankfully, the pads are easily removable in a manner similar to the Beyerdynamic DT-880 series models so experimenting with other styles of ear pads should be a simple matter.
The cable is the wide and flat 6 wire design similar to those found with most STAX models. The cables are somewhat heavy, but very durable starting with a 5- pin male DIN connector and a split roughly 18 inches from the north end into two 3 wire flats that terminate in the 3-pin female connectors.
Due to their low weight and moderate clamping force, I found that I needed to either place a portion of the cable in my lap or shirt pocket or the cable did tug at the cups and cause the headphones to shift on my head. Once I became used to this somewhat quirky feature, they proved to be rather lightweight and very comfortable, and I had no issues wearing them for extended listening sessions of over two hours.
Driver Technology
The heart of the SR-X1 is the newly designed round electrostatic driver (the SR models feature the round driver while the Lambda/Sigma models feature the elongated driver).
The stated design goal was to engineer a driver with a neutral sonic presentation, exceptionally low distortion, and solid dynamic capabilities. To make that happen, STAX redesigned the housing to minimize the seams between the layers and created an open back slit structure with uneven thickness that permits sound to pass more smoothly over the surfaces.
Even the internal wiring has been redesigned to keep it from impacting the sonic performance.
The new driver has a capacitance of 110pF and an impedance of 145k Ohms with a bias voltage of 580V DC. This results in a sensitivity rating of 101dB/100Vrms @ 1kHz.
This is clearly not something that one can drive with a Dongle DAC or smartphone – or even standard headphone amplifier. Those who wish to tumble down the electrostatic rabbit hole require something like the STAX SRM-400S (read our review) to make it work.
Listening
Electrostatic headphones or “earspeakers” are not known for their sub bass range impact and definition; unless we are talking about the new Audeze CRBN2 that toss that limitation into the dustbin of history behind the aforementioned In-N-Out Burger in Orange County.
The SR-X1 are a bit of a surprise in that regard, especially considering the size of the driver, and there is some sub bass information present. It’s not overly emphasized but it’s there. The SR-X1 follows the pattern set by its predecessors that delivers rather clean and fast sounding bass – but without a lot of weight behind it.
There is, however, more impact in the mid bass and that does give the overall bass range additional texture and detail. For genres of music that don’t rely on electronically produced bass, the overall tuning is rather acceptable, but those looking for hard hitting sub bass impact will find the STAX SR-X1 somewhat lightweight in that range.
The midrange is extremely well reproduced, but not over-emphasized. Those looking for a tonally accurate midrange with strong clarity and detail will be pleased by their performance with vocals and instrumentation in the range.
Male vocals have ample tonal weight and texture and those who focus on acoustic and electric bass material will notice that the SR-X1 deliver both with ample energy and rather accurately.
Bowing techniques for cello and viola are very easy to differentiate and the violin on the higher end had excellent presence and clarity. Guitar notes are delivered with a strong level of rasp and growl and acoustic guitars were clear sounding; with the amplifier influencing the degree of tonal weight.
The lower treble range has some additional emphasis giving female vocals more of a presence, pushing them forward in the soundstage of their male counterparts.
The very open and somewhat forward sounding presentation had me concerned that vocals would exhibit some sibilance or a nasal quality but that proved not to be the case.
Above the mild lift in the lower treble, the rest of the range drops back to a level roughly equal with the rest of the midrange. Percussion has good snap with cymbals sounding rather realistic.
With the treble range extending all the way to 41kHz, there is more than enough detail and airiness to keep these engaging but not fatiguing. The “sizzle” that can exist with some electrostatic headphones at the very top didn’t really materialize to a level that I found an issue – but I do think some might find it slightly hot.
The soundstage is rather spacious, with marginally more width than depth and a surprising degree of height. Above average instrument separation made seating the orchestra rather easy, and one could follow along when a musician moved around the stage.
Imaging was rather precise, placing every musician and instrument in its proper place within the soundstage.
The Bottom Line
When you consider that one can assemble a complete system comprising of the $535 SR-X1 and STAX SRM-270 Energizer for only $980 – the higher asking price of the competition might make these a better option.
The portable STAX SRM-D10 II which combines an energizer and 32-bit/385kHz PCM/DSD256 DAC allows one to take the SR-X1 on the road delivering one of the best experiences below $2,000 in the headphone category. But we would hesitate taking these on road due to the fragile nature of electrostatic headphones that are not really designed for the daily abuse of the office commute or travel.
Electrostatic headphones offer a very different perspective and if you have always wondered if they were for you – these are the best place to start without going broke.
Pros:
- Speed, detail, and transparency that can’t be matched by similarly priced headphones
- Tonal balance is rather balanced without any big dips
- More affordable than other electrostatic headphones
- Spacious sounding
Cons:
- Not suited for outdoor use or commuting
- Build quality does not match its high level of performance
- Bass lacks impact compared to other transducer types
- Requires an electrostatic energizer or amplifier which will add at least $450 to the system price
Where to buy:
- STAX SR-X1 – $535 at StaxHeadphones.com
- STAX Bundle Set SR-X1 + SRM-D10 II – $1,340 at Audio46
- STAX Bundle Set SR-X1 + SRM-400S – $1,580 at Audio46
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