Pros: clear, revealing, fast, large soundstage, cheap
Cons: lacks body/bass impact, cheap construction and pads, slightly bright
Note: All of my listening impressions of the Stax SR-202 were done with a Stax SRM-313 amplifier, which was hooked up to an AMB y2 DAC via the RCA input with SKW JIB braided interconnects. For the dynamic headphone comparison, a Schiit Lyr (with Sylvania 6BQ7A tubes) was used with the same DAC and interconnects.
First off, the driver unit: There isn’t really too much to say about the driver, it feels well built and looks beautiful in person. The potentiometer utilizes a double axis design, which means you either turn the whole knob to make the left/right channels louder. Or, you can move an individual portion of the knob to make the sound louder in only one side of the earspeaker. The potentiometer is smooth and isn’t too stiff or firm. Case feels solid and it has a bit of weight to itself, overall, build quality is pretty good.
Now, sound wise, I’ve never owned any other electrostatic amp. But, the SRM-313 seems to get the job done fine. It has more than enough power to drive the SR-202 to ear damaging levels. I never find the need to max out the volume. Modern recordings usually have the knob dialed in at 2.5/4. For recordings with a large dynamic range, the volume is usually at 5-7 on the knob. Another plus, background noise is 100% absent, absolutely nothing, even with the volume at 100% with no music playing. That is pretty impressive, considering I’ve heard single ended amps (though not electrostatic) that cost to $1,000 that have background noise even though I used the same exact interconnects and DAC in my system when testing them.
Onto the Stax SR-202 earspeakers
Build: Build is OK, my main problem is that the whole earspeaker is constructed of plastic. The plastic used for the housings of the diaphragm do feel solid in the hands, but, the plastic that is used for the gimbals and the headband feel cheap and fragile in comparison to the stronger plastic that holds the diaphragms.
Comfort: Weight distributed evenly, these are about 300 grams. However, the suspension strap relives most of the weight. Clamping force is perfect, they don’t feel like they’re strangling my face or that they’re going to fall off. Compared to the HD600/650, comfort is on par with the Sennheisers. You get more clamp with the HD600/650 at the cost of having nicer earpads, with the Stax, you get less clamp but bad pads (though Stax sells upgraded, real leather pads)
Now, the sound quality.
Lows: Quality>Quantity. The bass of the 202s has excellent extension, speed, and texture. They only lack perceived impact, compared to other headphones, these do not have a mid-bass hump which may give you the impression that they lack a bit in the low end. Due to the nature of the electrostatic driver, the bass is insanely fast. Listening to metal or techno, the bass of the HD600 almost sounds monotone and blurred in comparison. Bass goes down to 20hz, at which you can literally feel the bass on your cheeks at that frequency unlike the HD600 which has absolutely no bass that goes that low.
Mids: The mids are good, they aren’t recessed nor overly warm and rich. Vocals are palpable, but slightly brighter, thinner, and more sibilant than what I would consider natural. Instruments are rendered pretty realistically and naturally, minus a slight lack of body and slightly overemphasized treble. This makes some instruments sound a bit wonky (chimes & cymbals). The thinner sound, however, kind of enhances things like the acoustic guitar, strings, harp, etc. The Stax sounds really precise with these kinds of instruments, in comparison to the HD600 which adds a ton of extra reverb and doesn’t separate the individual plucks of the strings as gracefully as the Stax.
Highs: The highs are on the brighter side of neutral. Due to this, these are not very forgiving of poor quality recordings vs other headphones I've heard (HD600, LCD3, HE-500). I find the treble to be manageable but cymbals and sibilance are exaggerated on the SR-202 to the point of causing fatigue on some recordings. Otherwise, the treble is mostly tolerable and has good extension, it's just a touch too peaky.
Soundstage: Fairly large and diffused. The SR-202 has good width and can easily separate complex musical tracks. Unlike the HD600, the SR-202 can give every instrument in an orchestra their own personal space while the HD600 sort of mixes everything together. The soundstage of the SR-202 extends a bit out of your head, giving it a nice sense of 3D space a.k.a a surround sound effect. Though, they are not very forward like the HD600. You feel like you're a couple seats back with the SR-202 than when you listen to the HD600.
Compared to dynamic headphones.
This is a comparable combo cost wise to the Stax. In fact, the Stax system, composed of the SRM-313 + SR-202, was actually cheaper (I bought both systems used for about the same cost). The dynamic setup, as stated before, is a Schiit Lyr (Sylvania 6BQ7A tubes) + AMB y2 + SKW JIB ICs. My original intentions were to do song comparisons + long term back and forth listening (about 3-4 weeks) but I ended up selling my dynamic setup, so, this portion came very early.
Lows: The Stax easily beats out the HD600 in the low frequencies. The Stax has more extension, going down to 20hz and allowing you to feel the super low sub bass. In comparison, the HD600 rolls off at 40 Hz and there isn't anything happening under 40hz. Speed wise, the Stax again wins. Listening to upbeat techno or metal easily shows you that the Stax can keep up. Bass almost sounds monotone and blurred with the HD600 on these genres compared to the Stax.
Now, the HD600 does have some positive traits vs the Stax in the bass department. For one, the HD600 has more of a mid-bass hump, which may be a pro/con based on your tastes. The hump on the HD600 gives you more of a tactile feel in that area. The Stax is more tactile (meaning you can feel the bass) with very low notes (under 40 Hz) while the HD600 has more tactile bass in the higher bass notes (40-100hz+).
Mids: This is probably one of the most significant differences that sets apart the HD600 and Stax. The Stax almost sounds hollow in comparison, it is very hard to get accustomed to the mids of the SR-202 after owning the HD600 for well over a year.The midrange of the HD600 is very full and rich. While, on the Stax, everything sounds thinner and less rich, what I'm trying to say is that the Stax lacks body, at least when compared to the HD600.
Highs: The Stax is brighter and a bit more fatiguing. Not so much so that it causes discomfort, but, my main problem as I said before is that these overemphasize cymbals and sibilance on less than stellar recordings. There are a lot of albums that I can't listen to any more on the Stax, because they are too bright (which is mainly due to the poor mastering). The HD600 has less sibilance and more relaxed treble in general vs the Stax.
Soundstage: The Stax has a wider soundstage, it was very obvious switching back and forth that it had a more diffused soundstage. In complex recordings, the Stax was able to separate everything so that instruments had their own sense of space, the HD600 failed at this in comparison.
Some positive notes on the HD600: it sounds more in your head and can be more exciting because of this. I feel more involved with some music since it sounds less diffused, however, on orchestral music (Wagner, Beethoven, Stravinsky) the HD600s smaller soundstage wasn't tolerable after hearing the Stax. Everything sounded mixed and crammed with each other.
Apart from width, depth seems similar and the difference is subtle in that area.
Timbre: Stringed instruments (acoustical guitars, harp, etc.) sound a bit better on the Stax in my opinion. You can hear every individual note plucked and the notes carry a bit of a sharp sensation to them (not really sure how to describe it). The HD600 with the harp, acoustic guitar, etc adds extra reverb and gives these instruments too much body. All the strings plucked on a harp sound mashed together, the Stax separates every string whereas the HD600 combines them into a whole.
Other instruments, like the organ/sax/trumpet sound a bit better on the HD600 IMO. The extra body makes them sound very full, I dislike how the Stax lacks body on the lower notes of an organ/piano.
Conclusion versus the HD600.
The Stax is technically more proficient than the HD600. It was faster, cleaner, had better extension on both ends of the sound spectrum, a larger soundstage, and less distortion. Yet, I didn't enjoy them as much as the HD600. Some albums were rendered useless because they are not forgiving, music was more distant and less exciting, and the headphone just seemed to lack any sort of emotion to the sound. It sounded a little too analytical sometimes. For most music, its technical finesse was just too much. Although, on nice recordings, the extra detail of the Stax was extraordinary.
The HD600, while being technically worse than the Stax, was more enjoyable. I can listen to less than perfect recordings and the HD600 is forgiving of them, the sound is warmer and fun, and I just feel more engaged with the music. The strength of the HD600 isn't its technicalities, but its tonality. I have yet to hear any headphone, that to my ears, retains the HD600's tone while improving on its technicalities, and I've tried many headphones with costs ranging from $400-$2,000. These were the LCD3, HE-500, HE-400, SR-202, and in the future it will probably be a HE-560 as well.
Anyway, if you made it this far, thank you for reading through my massive wall of text. I hope you enjoyed the review.
Here are some quick pictures of the SRM-313 and SR-202.