STAX SR-003 MKII In-Ear Electrostatic Ear Speakers.

Hot on the heels of the D10 review, I get to grips with the SR-003 MKII portable in-ear ear speakers…

This review is sponsored by STAX.
Thank you to Audrey & Kay, who have been very kind and shipped me these in-ears.
The SR-003 MKII retail for $284 and can be found here:
I will note here that although this is a sponsored review for STAX, I have been honest and unbiased in my opinion.

Review equipment:
STAX cable accessories.
Astell & Kern AK70.
iBasso DX80.
iPad Pro.
Audioengine B1.

Various Hi-Res files on the AK70 & DX80.
Qobuz Studio Premier on other devices.

What’s in the box:
STAX SR-003 MKII in-ear ear speakers.
Ear tips.
Plug cover.

STAX provide everything you need to use the 003 MKII’s with ease and comfort.

The ear hooks are from a different in-ear that I custom fitted.

Spec & features:
Type: push-pull electrostatic, canal-type inears.
Frequency response : 20 – 20 kHz (±4dB).
Static capacity : 44pF (including attached code).
Sound pressure sensitivity : 110dB/100V r.m.s. / 1kHz.
Bias voltage : 550V – 580V.
Ear piece : L/M/S size made of silicone rubber (M size equipped at factory shipment).
Cord : 5-pin for STAX PRO bias, 6-core parallel, total length 1.5m.
Weight : 38g (including code), 12g (main part only).
Dimension: 28mm (diameter).
Overhead arc weight : 15g.

Build and finish:
I already own the previous version of these which has a proprietery plug for use with a portable driver.
The same high quality of craftsmanship is apparent here with a premium finish.
They are lightweight and fitment is perfect.
I do wish STAX would include a carry pouch or case for these smaller in-ear’s & maybe that’s something that can be thought about in the future?
I also think the headband is great, however the clamping force is quite aggressive so it’s sometimes uncomfortable to use.
This is what led me to utilising a set of ear hooks from a different in-ear and I believe is something else STAX could think about for a new version somewhere down the road.
All in all though they’re made extremely well and well thought out.

The 003 MKII are a comfortable in-ear once you figure out the best way to use them for yourself.
Once I figured which ear tips were the best fit for me the 003 MKII’s were very comfortable and could be worn for hours of use with no fatigue or discomfort.
However I will say here as before, the headband, although a great idea, does have aggressive clamping force so may not be comfortable to use for some users.
This is where the aftermarket ear hooks came into play, and is something I really think STAX should consider in the future.


The 003 MKII’s offer a wide spacious soundstage with well defined separation.
We are rewarded a warm, textured low end with a decent punch.
Mids are resolving, organic & airy.
Then we finish off with fast yet smooth highs dusted with a little sparkle up top.

Final thoughts:
We’re getting a lot of electrostatic in-ear for our buck here.
They sound like a product that belongs in a much higher price bracket.
The only complaint I really have is the clamping force of the headband and there being no carry case or pouch.
Otherwise these are an excellent purchase and I’ve enjoyed them so much that I’ve bought a pair myself.

As always a massive thank you to all of my readers, contributors and sponsors!
Please remember to like, follow, subscribe and share.

All my very best.

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