STAX SRS-3100 Electrostatic Earspeaker System. (SR-L300 / SRM-252S)

This time around, STAX send me out their understated entry level electrostatic ear speaker and driver system.

This review is sponsored by STAX.
Audrey, Kay and STAX have been very kind and shipped out this ear speaker and driver system.
The SRS-3100 retails for $1,140.00 and can be found here:

I will note here that although this review is sponsored by STAX, I have been honest and unbiased in my opinion.
You will find a link to STAX if you’re interested in their products at the bottom of this review.

Review equipment and software:
STAX SRS-3100 electrostatic ear speaker and driver.
Cambridge Audio DACMagic 100 USB DAC.
MacBook Air running Qobuz Studio Premier.
Audiocrast USB cable.
Cambridge Audio RCA interconnects.
Tacima 6 way mains conditioner.

Various High Res and Redbook ( CD ) files on Qobuz Studio Premier.
A few links to some of my playlists and a few from others:

I’d like to quickly thank David Solomon & Qobuz for our ongoing partnership.
Their support of The Audiophile Cafe has been stellar and is much appreciated.

What’s in the box:
STAX SRM-252s Electrostatic ear speaker driver.
STAX transformers. Japanese and UK version supplied.
STAX SR-L300 Electrostatic ear speakers.

SR-L300 ( Earspeaker )
Type: push-pull electrostatic, oval sound element, rear open-air type enclosure
Frequency response: 7 – 41,000Hz
Electrostatic capacitance: 110pF (including attached code) 
Impedance: 145kΩ (including attached cable, at 10kHz) 
Sound pressure sensitivity: 101dB / input 100Vr.m.s. / 1kHz 
Bias voltage: 580V DC
Ear pad: high-quality artificial leather (for SR-L300 only)
Cable: parallel 6-strand, 2.5m full length, low-capacity special wide OFC cable
Weight : 448g (including attached cable), 322g (without cable)

SRM-252S ( Energizer )
Frequency response: DC – 35kHz
Rated input level: 125mV (at 100V output)
Gain: 58dB
Harmonic distortion: 0.01% or less (at 100Vr.m.s. / 1kHz output) 
Input impedance: 50kΩ(RCA)
Input terminal: RCA x 1
Maximum output voltage: 280Vr.m.s. / 1kHz
Standard bias voltage: DC580V
Power consumption: 4W
Operating temperature / humidity: 0 to 35 degrees C / less than 90% (non condensing)
Dimension: 132 (W) x38 (H) x132 (D) mm (protruding portion not included)
Weight: 540g

Build and finish:
Being my second system from STAX, as with other brands, this is an opportunity to get a better insight to the brands quality control.
Just like before I’m very impressed with the build quality of both the driver unit and the ear speakers.
I’ve seen and heard many reviewers give STAX a hard time over their build quality and to be honest I don’t get it. I may be sponsored by STAX for this review, however they never ask for a positive review, there are never any conditions in place.
And they know I will always be unbiased and honest when I write these pieces.
So I can say now that I am honestly impressed with STAX’s craftsmanship and attention to detail.
The SRM-252s driver unit is a solid and robust little box with a housing, ports, knobs and switches finished to the highest standard. The power switch/volume pot is smooth as butter with a nice firm switching action.
The RCA ports and power port around the rear are sat firmly in place and don’t move or wobble when plugging or unplugging cables.
On the base are four sorbothane feet which hold the unit in place with no slippage.
On the front plate we find a simple layout of Volume pot/Power switch, Power LED and the STAX pro output port. Two hex bolts hold the plate in place and the STAX logo is printed in the centre without being too large or obnoxious. It’s good to note here that the Power LED is a nice tone of green and is neither too bright or too dim. Which is something other brands still struggle with, either being too bright or dim, and often using harsh colours that can be jarring when in use. With the SRM-252s in my mind being a desktop solution, this is something I take seriously!
And finally, I did wonder whether this unit would get very hot and I can confirm it does not. It gets warm when in use but nothing to complain about.
On to the L300’s…
The SR-L300 ear speakers or their siblings are something I’ve wanted to experience and own for a very long time, ever since the day I came across the brown Lambdas online in the early years of the internet.
The design is unique to say the least and I personally love it. Like the SR-009’s I have here at The Audiophile Cafe HQ, they have that ribbon cable that you don’t see anywhere else, and it’s a very good cable. It’s made well with a tough feeling rubber sleeving. The plug itself is constructed to a high standard and has an industrial feel to it. In fact the entire plug and cable do.
The housings and headband are a tough plastic that is nicely finished with no rough or dodgy edges to be found. I don’t know how easily they would snap as I don’t intend to drop them or twist them to their limit as some reviewers do. I don’t see these as a portable ear speaker, neither do I see myself moving around my home wearing them.
In my case I’m using them sat in my listening space, with the system next to me on a solid pine table. I have the STAX ear speaker stand and plastic cover right next to me so I can safely put the L300 away when I’m not wearing them. In my opinion, if you use your common sense and take care of your gear, you’re less likely to do any damage.
I love the uniqueness of STAX ear speakers. Aside from the sound they produce ( which I’m coming to in a moment ) they’re a head turner. Any visiter I have here is always interested in their “weird” looking design and appearance, and want to hear them.
In my my mind they scream “Audiophile” and they have certainly earned that label!

There’s really not much to say here, setup is very straight forward.
Plug your source in and the ear speakers, power on and you’re done.
On a side note, the SRM-252s has a parallel output, meaning you can run a cable from the driver unit to your pre-amp or maybe another headphone amplifier. One very handy thing about this feature is if your SRM-252s is powered off, it doesn’t interfere with the signal being fed through the parallel output. So you don’t need to have it on for this to work. Nice touch STAX.


Surprisingly, unlike the SR-009 the L300 have quite a firm clamping force. Which at first concerned me as I wear glasses almost all the time now.
My concerns however were quickly dissipated when I put the L300’s on my head.
Just like the SR-009 the comfort here is on another level. The L300’s sit nicely on my head with the headband hardly noticeable. The “Cups” sit over my ears like pillows with the ear pads being luxurious and feeling very premium. Again my ears don’t come into contact with the “Staters” although there’s probably only a few mm’s in between them and the outermost parts of my ears. I’ve found another “headphone” that essentially disappears on my head once they settle in. Also I found little positioning was needed to get the correct level of comfort and image.
I found I could wear and listen to the L300 for a good 3 to 4 hours with no discomfort and zero fatigue.

Where the SR-009 take every headphone and amp that I own and move everything up into another realm, the SR-L300 along with the SRS-252s take a different fork on that path.
Where the SR-009 are spacious and wide open, the L300’s have a more focused soundstage, though still wide and with good depth.
Like the SR-009 the L300 are a dynamic ear speaker, performing superbly throughout the frequency range. However, with a slight improvement in one regard and a small step back in another…
The L300 comes out on top here with a deeper and more lively low end. The texture and clout of the SR-009 is still present, but we also have a lower reaching bass with lower sweeps without losing any detail. I noticed this more when I listened to some Drum ‘n’ Bass tracks and a few techno mixes. The highs are crisp and clear with a beautiful sparkle. Compared to the SR-009 the highs are rolled off, but not by much.
Mids are more forward and less organic sounding, that’s not to say they don’t sound good. They sound great, smooth and full bodied. And I found this a really pleasing trait when listening to live acoustic performances.
I’d say they sound more grounded and have a “flatter” neutral tonality to them.

Final thoughts:
“It’s like driving a perfectly brilliant Mercedes daily drive throughout your life, then swapping it out for a Ferrari.” – Those were my exact words when you go back and read my review of the SRM-700S and SR-009.
If the SR-009 and SRM-700S are a Ferrari, the SRS-3100 easily earns it’s place as that “perfectly brilliant Mercedes”
If I were to keep these I’d be tempted to use them on my desktop along with my Mac and gaming PC setup. The comfort and sound they produce would be ideal for that system and its various use cases.
In all fairness, it’s not entirely fair to compare the L300 to the 009’s as I have. The L300 is a $455 ear speaker vs the SR-009 coming in at $3,699. It’s a huge difference in cost.
And I have to say, The L300 perform more akin to a $1000 headphone and outperform a certain dynamic headphone I’ll be reviewing soon that comes in at £1,799!
Would I recommend the SRM-3100 ear speaker and driver system at $1,140?
Yes. Against every dynamic or planar magnetic headphone I own, currently have in for review
or have heard either in a review or previously owned, the L300 outperform every single one of them. Even my beloved Sony MDR-SA5000s.
They make the perfect desktop, bedside or sofa-side system for lively, engaging sound reproduction.
If you want to have a $2,000 plus sounding headphone system but for less budget, you can’t go wrong here.

Thank you to my readers for your ongoing support!
Please be sure to subscribe, like, follow and share the blog.
Thank you to Qobuz for continuing to supply The Audiophile Cafe with some truly remarkable music!
And thank you to STAX for making this possible, not only that, but also for sponsoring The Audiophile Cafe. I truly appreciate the level of support and help you have given to me and the blog!

All my best. Paul.