Stax SR-007 "Omega II" Open-Back Electrostatic Earspeaker

General Information

Type :push-Pull Electrostatic Earspeaker
Frequency Response :6 - 41,000Hz
Impedance :170k Ohms (10kHz)
Sensitivity :100dB / 100V r.m.s. 1 kHz
Bias Voltage :580V DC
Left & Right Channel Identification
:Left (L) and Right (R) indicators are provided at the cable entrance points on the Earspeakers. Left channel cable is marked with a solid Line. Right channel is marked with a dotted Line.
Ear Pads :Crafted from high quality artificial leather for durability and comfort.
Cable :Low capacity wide format, PC-OCC (Pure Crystal Ohno Continuous Casting) 2.5m/8.2ft
Ambient Temperature & Humidity :0 to 35ºC / 90% max. without condensation
Weight :12.9oz without cable / 1.1lbs with cables

Latest reviews

Pros: As natural, pure and transparent as I've ever heard a headphone to be. Solidly built. Comfortable.
Cons: Demanding. The "STAX fart".
If performance is based solely on ultimate transparency, then this is the best headphone I've ever owned and/or listened to. That includes the SR-009. Superb clarity and resolution without any hint of treble brightness or fatigue. Its purity of tone is simply astonishing; it's smooth, organic, airy and fast all at the same time. It adds little to nothing of its own, and neither does it subtract anything from the richness of the music. And for an electrostatic headphone, the bass performance is superb. Tight (!), fast and impactful with plenty of warmth and body. It extends all the way down into the lowest octave, albeit not with quite the same weight and force of an Audeze planar. 

The 007 is built to last, with materials being mostly magnesium and premium supple leather. Solid to the touch and highly comfortable for long listening sessions. 

Very demanding of amplification quality and power, especially in terms of getting the bass right. But rewarding in the end. 

"Farts" when moved/pressed on the head but it's a small price to pay for the sound quality on offer here.
I love this freakin' thing. You will NOT be disappointed with this headphone. 

Pros: Superior treble detail and extension, bass depth and impact, neutral neuanced mids
Cons: Slightly uncomfortable, neutral mids might feel recessed, expensive
This is not really a review, just some inital impresions I'd like to share with fellow head-fiers. I've spent some hours with the SR007 mkI and the SRM007 amp. I also compared the mkI and mkII briefly, and main difference, though subtle, was that the mkII is slightly more forward and bright sounding. I preferred the slightly more smooth mkI. 
I've listened to the Stax O2 a couple of times before, but recently I was lucky enough to take it home for trial. When I rigged up the stax rig next to my HD650/Woo WA2, I was eager to see how much more I'd like the Stax rig.... Here's my short comparison
1) o2 is of course substantially more detailed
2) o2 has blacker background
3) o2 has better soundstage, but not by the large margin I'd expect
4) o2 has deeper bass by far and makes music that I really only enjoy on large speakers shine
5) HD650 is way more comfortable. Main issue is velour pads and that the o2 cups don't swivel
6) HD650 is to me less fatiguing. Every time I switched back to the HD650, I felt relief.. The Stax  creates a slight vacuum, and is brighter feeling (though it isn't bright by any high end standard)
7) HD650 has better midrange tonality. The o2 has more detail, of course, but the HD650 has a better flavor. The o2 feels recessed, presenting a "neutral" or "cold" midrange, when the HD650 is warm and natural feeling. 
Despite the obvious technical advantages, I preferred the warmness and natural feeling of the HD650, though I really miss the smooth treble detail and powerful bass extension of the O2. 
Again please take this "review" with a grain of salt :) But I wrote it as a reminder that expensive and technically superior isn't necessarily subjectively better - cost no object...
Thanks for taking the time to share this!
Pros: airy, fast, detailed, pin-sharp imaging, full-bodied, seductive midrange
Cons: sensitive to...everything, some may find it too warm, lots of power needed for bass control
Some love it, some don't but there is little doubt that this is one of the top-tier headphones out there and one that is not so rare, so if bought second-hand the price of the headphones and amp are very much comparable to a top-level dynamic/planar setup which makes these a compelling option.
The fit is a little tricky at first, but once it is set up it feels very comfortable on the head. It is important to position the transducers close to the ears. The build quality is pretty solid and the finish looks great apart form the cable entry which is prone to break if one is not careful.
Technically it carries all the aspects e'stats are famous for. So it is very airy and presents masses of detail but in a fairly unobtrusive way. It is quite sensitive to what components are in the signal chain and I would say, the simpler it is, the better.
The O2 Mk1 definitely has a distinctive sound that some may call "warm". That is, it injects life and emotion into the music even when it is not recorded that way and adds a bit of extra weight to the instruments. It has that creamy, smooth type of presentation which is easy on the ears so which makes it more forgiving, apart from a treble that is slightly uneven and can get "caught out" on some "harder, more digital" recordings.
The bass has a good amount of texture and weight and fairly punchy by electrostatic standard but could be more controlled.
Because of its own sound character and power need to control the bass, a linear powerful solid state amp should be a perfect match, however if some would like an even more "old-school" tubey sound they might like it with a SRM-007t or other hybrid/all-tube amps as well. The SRM-717 is somewhere in the middle carrying the solid-state refinement but also adding a little extra warmth to the O2 Mk1's generally warm sound and makes the soundstage slightly diffused and it does not have full control over the bass.
So how could I sum this one up?
Well, I think the SR-007 Mk1 is definitely "The Dark Knight of electrostats"
Just listen to the main theme with these, and you will hear what I meant :) So if you happen to like that sort of thing, you will not be disappointed.
(Main test setup was: Lavry DA11->SRM-717->SR-007)
Nice review, informative and well written. Thanks.
I would love to own a set someday! I have owned electrostatic speakers and loved them!
Thank you for impressions and the review!
Thanks for your honest review as it is very informative. I found the bass & soundstage get better when the O2 + SRM-717 runs in balanced configuration.


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