STAX SR-X9000 EARSPEAKER REVIEW

John Scott spends some quality time with the flagship SR-X9000 earspeakers from STAX.

Back in 1981 when I first started thinking about putting together my first proper audio system, I spent a lot of time and money reading the HiFi press of the day (money, that in hindsight would have been mostly better being set aside for the actual system). It wasn’t all money wasted though, because as well as learning about the kinds of kit that I could possibly afford I also learned about the stuff that was out of my reach but that I could dream about one day possibly possessing.  Where would the audio industry be if we didn’t all have those dreams, eh?

A more conventional design than John remembers from the past

In my reading, the name STAX emerged as the product of choice for the serious headphone listener. In my naivety, I briefly wondered if the company had any connection with the American soul music record label that I had recently become familiar with. It seemed unlikely, even to me, and of course, proved not to be the case. What I did take away though, from the various articles I read, was that STAX headphones (or earspeakers to give them their proper name) were: A) expensive, B) oddly shaped compared to any other headphones I had seen and C) required a special amplifier to drive them. It was also clear that the people who liked STAX earspeakers liked them very much indeed and that there was genuine value and purpose to be had from investing heavily in a high-quality headphone system. But that wasn’t for me with my tiny budget and I somehow doubted that it ever would be.

Fast forward more than forty years and out of the blue came the opportunity not just to review a pair of STAX earspeakers but to review the company’s flagship SR-X9000 model.  Obviously, I jumped at the chance.

While some things have changed (I’ll tell you in a minute), some things have remained the same: the SR-X9000, along with other models in the STAX range, still requires its own dedicated amplifier due to its electrostatic design. Fans of electrostatic loudspeakers will be familiar with the speed and transparency that are part and parcel of this technology and these are the same qualities that have been prized by STAX aficionados over the years, but it is this electrostatic technology that necessitates a particular type of amplifier to drive the earspeakers. I was supplied with STAX’s SRM-T800 drive unit to carry out amplification duties.

If the need for a dedicated amplifier remains, what is it that has changed? The STX earspeakers I was familiar with were large rectangular boxes that sat on each ear, literally making it look like the wearer had a pair of small speakers glued to their head. The SR-X9000 has more conventional round earpieces, considerably more attractive in my opinion and a bit of research revealed that STAX have in fact always made round earspeakers.

An exploded view of the driver assembly

UNBOXING AND SET UP OF THE STAX SR-X9000 EARSPEAKERS 

Before we get to the SR-X9000, we need to talk about the SR-T800 drive unit. This is a hybrid unit with two 6922 dual triode valves in the input stage and a class A output stage. The SRM-T800 is a fairly substantial unit weighing 7.3kg and measuring 320 (W) x 103 (H) x 395 (H) mm. Set up was no more complicated than that of a standard integrated amplifier. Balanced and unbalanced inputs are catered for (3 inputs in total). The front panel has outputs for two sets of earspeakers, should you live with someone who has their own pair of STAX earspeakers or have a friend who likes to pop found with theirs so that you can both sit in splendid isolation, listening at the same time. (Yes, I know.  But I guess there must be a use case for this feature or STAX wouldn’t include it). A dual-gang volume knob allows balance control if required. STAX recommends turning the volume to zero on power up and then increasing it to the required level.

John found the Stax earspeakers very comfortable over long periods

As for the SR-X9000s, the earspeakers come in a rather ordinary-looking branded card box which opens to reveal a rather lovely polished wooden box featuring a brushed brass effect plate with the wording “SR-X9000 electronic earspeaker” inlaid in black lettering along with the STAX logo and “made in Japan”. The box is of a high quality, befitting the earspeaker’s flagship status but, presumably as a result of being a demo model and having had a fair amount of handling, mine had a dent in the side and the lacquered surface does look like it could be quite easily damaged so I would advise purchasers to take good care of the box as part of a premium package.

Internally, the SR-X9000s are firmly secured within foam padding along with 2 cables, one of 1.5 meters and one of 2,5 meters, allowing a good degree of versatility in siting the SRM-T800 drive unit and my preferred seating/listening position. The cables are a flat, six-stranded design (think those liquorice rolls with a beaded aniseed sweet at their centre) made from 99.9999% pure copper.

BUILD QUALITY AND COMFORT

You would expect any product at this price point to have excellent build quality, but when the product in question is the flagship model of a company with Stax’s reputation then you can understand that my expectations were particularly high. Thankfully, the SR-X9000 doesn’t disappoint. Up to this point, my impression had been that STAX earspeakers very much favoured function over form. However good they sounded, they were unlikely to be considered as being attractive. The SR-X9000s combine aluminium, stainless steel, and leather into a luxurious, high-quality product that accommodates the requirements of its electrostatic design without compromising on looks.

Electrostatic drivers consist of a thin membrane placed between two charged plates which act to vibrate the membrane. STAX uses a charge of 580 volts to alternately push and pull the membrane to produce sound. Due to its delicate nature, the membrane needs to be protected from damage. Equally, the user needs to be protected from the charged plates or “stators”. And all of this has to be done in a way that does not adversely affect the sound quality of the earspeakers. STAX have refined a layered metal-mesh design for their stators over decades, resulting in the four-layer version that appears in the SR-X9000s. Further mesh protection is required on each side of the stators to protect the user and STAX have introduced a non-parallel design, intended to reduce sound reflection within the earspeaker.  As these are open-backed speakers, this mesh work really needs to be aesthetically pleasing as well as practical and the SR-X9000s totally deliver in this respect – I think they look great, combining a solid build with visual finesse.

While good looks are nice to have in any piece of HiFi equipment, where headphones are concerned, comfort takes a much higher priority; no one wants discomfort distracting from their musical enjoyment. At around 430g, the earspeakers are of average weight for their size; you know you are wearing them but there is no sense of fatigue even after several hours of use. Unlike some headphone cables, the SR-X9000s flat cable did not give a feeling of adding weight and dragging the headphones downwards on the ears. A wide leather headband and finely-stitched leather earpads help prevent that clammy feeling that can sometimes occur when synthetic alternatives are used.

The included cable attaches to a special energizer amplifier from Stax

SOUND QUALITY

I’m not a great fan of HiFi test records, but when swapping kit in and out of a system I often find it useful to do a channel ID test just to make sure that I have connected everything up correctly. My channel ID of choice comes from Dr Chesky’s Sensational, Fantastic, and Simply Amazing Binaural Sound Show! album. In this test, Dr David Chesky explains that he is standing in a cathedral.  As he speaks, he walks closer and closer to the microphone until he ends up whispering in the listener’s ear. I have used this track with several pairs of headphones but this was the first time I could have sworn that I actually felt Chesky’s breath on my ear. The hairs on the back of my neck stood up. No one (I hope) buys headphones of the calibre of the SR-X9000s to listen to test records though and so it was time to move on to some proper music.

Electrostatic speakers have a reputation for being suited to classical music but I ignored this as a starting point and got stuck into Get Lucky from Daft Punk’s Random Access Memories album instead. Heard on the radio, this is a fairly straightforward pop song but the SR-X9000s laid out all the subtle interplay between the guitars, bass, and drums, revealing the skill that went into the song’s production. Sticking with the album, the track Giorgio By Moroder moves from a simple spoken word intro in a nightclub setting to an increasingly complex mix of electronic, electric, and acoustic instruments where the drums become increasingly distorted until they turn into slabs of noise. I had wondered if this might have taken the SR-X9000s out of their comfort zone but they rose to the challenge, effortlessly delivering the speed and attack of the transients as the drums morphed from acoustic to electronic.

Moving to a bit of reggae, if Linton Kwesi Johnson’s Iron Bar Dub lacked some of the sense of moving air that you get from loudspeakers in a room, bass extension was deep and well controlled and LKJ’s powerful vocals were clearly presented in front of the music before spiraling off in a heavily echoplexed dub style.

These are an open back design headphone

Finally, it was time to see how the SR-X900s fared with what many would consider their forte; classical music. I began with Alice Sara Ott’s live recording of the solo piano version of Mussorgsky’s Pictures At An Exhibition. In a piece that ranges from delicate single notes to complex chordal work, the piano held its position within the soundstage with the acoustics of St Petersburg’s Mariinsky Theatre around, in front, and behind it. Sticking with Pictures At An Exhibition I switched to an orchestral version, Leonard Bernstein with the New York Philharmonic. The change in the acoustic was clear to hear and the various sections of the orchestra were clearly laid out inside my head. Closing my eyes, it was easy to imagine being present at the recording.

CONCLUSION 

Given STAX’s reputation, a new flagship model naturally has high expectations to live up to. It’s worth mentioning at this point that STAX had also supplied me with a pair of SR-L700 Mk2 earspeakers so that I would have a baseline to reference against. The SR-L700s were great – I’d have a pair in a heartbeat, but the SR-X9000s were just head and shoulders above them in every respect; build quality, comfort, and sound quality.

You need to be a seriously committed headphone user to consider the investment that a pair of SR-X9000s and accompanying amplifier involves but if you are, start saving up now because STAX’s top earspeakers need to be on your audition list.

AT A GLANCE

Build Quality:  

Far too refined to shout, these earspeakers whisper quality at every opportunity

Solidly built, but with an air of delicacy, you’ll feel like you are indulging your ears with every use

Sound Quality: 

Outstanding speed and dynamism

Bass is uncoloured and fast

Incredible level of detail will have you revisiting your music collection

Value For Money:  

VFM does not really apply here! There is no world in which this product can be considered as a bit of a bargain. However, if you decide that you need them then nothing else will do.

You get what you pay for.

We Loved: 

I genuinely loved everything about these earspeakers.  However…

We Didn’t Love So Much 

The combined outlay required to purchase the SR-X9000s and accompanying SR-T800 amplifier will put them beyond the reach of all but the most committed, but that is an observation rather than a criticism.

Elevator Pitch Review: You don’t build a reputation in the way that STAX has without continuously evolving and improving. The SR-X900 is the current expression of the best that the company has to offer. The headphone equivalent of a luxury car, it will be bought by those who can and dreamed of by those for whom it is beyond reach.  And if like me, you are one of the dreamers, the more attainable SR-L700 Mk2 is a great product in its own right.

Price: US$ 6 200. £5 195

John Scott

SUPPLIED BY STAX