Baby Stax

stax_baby_3The Stax SR-001 Mk2, also known as the Baby Stax, is definitely a unique product. Along with the Stax SR-003, they are the only electrostatic earphones available in the market. While the SR-003 is designed to be driven from desktop amplifiers, the Stax SR-001 Mk2 comes with its own portable, pocket size, electrostatic amplifier. At the retail price of roughly $350, the Stax SR-001 Mk2 system competes with other top of the line IEMs.

As I have written on the $300 IEM shootout, the Stax definitely has some areas where its superior than the dynamics or balanced armature IEMs. Furthermore, as more and more people pair their IEMs with a portable amplifier, the Stax system comes out cheaper, as the $350 includes the amplifier.

The Baby Stax comes in a brown box with the Stax product description label on it. Somehow the spartan box gives an impression of an all-business device. The Baby Stax comes attached to the headband, and you can use it like a portable headphone, although the headband doesn’t fold. When you remove the driver units from the headband, it looks like an earbud with an oversized driver housing. A portion of the housing goes into your ear canal, which qualifies the Baby Stax to be an IEM device.

stax_baby_6Being an electrostatic earphone have its own pros and cons. Since electrostatics require a much higher voltage than dynamics, they cannot be driven from a regular dynamic amplifier, an iPod, or a regular headphone jack. This means that the SR-001 Mk2 needs to always be paired with the SRM-001 portable amplifier. While the SRM-001 amplifier is quite compact and lightweight, people who uses their IEMs for jogging and going to the gym would not want to use the Baby Stax. Though the SRM-001 is bigger than a lot of portable amps, it is lighter than a lot of portable amplifiers, and carrying it in your pocket is not so much of a hassle due to the light weight. The shape is also a bit curved, another feature that makes it fit well in your pocket.

Another feature of the Baby Stax is that it’s an open design IEM, and like an open design headphone, it leaks sound from outside, though not so much the other way around. This gives the baby Stax a much more open and natural sound compared to traditional sealing IEMs. I know that for some people, a sealing IEM may not be needed, and can be a nuisance sometime, as you have to constantly remove them from your ears whenever someone approach you for a conversation. Despite being an open design, I find that the baby Stax works fairly well in outdoor applications, perhaps due to its in-the-canal design, thus you don’t have to blast the volume very high even when listening to it outdoors. The fit is comfortable to my ears, and definitely better than the Etymotics ER4P or the UE Triple.Fi 10.

Like all Electrostatics, the Baby Stax shines in presenting a natural and open sound that makes you forget that they come from a set of IEMs. I think this is the biggest factor that draws me in to the Baby Stax, as all the other IEMs fail to present a natural and open feeling given by the Stax. If I have to pick an IEM that sound closest to the Baby Stax, it would be the Westone UM3X. Both have a fairly neutral frequency curve, with a good body and slightly warm tonality. Although the UM3X have better treble and bass extension than the Stax, I am won over by the Stax’s spacious and open presentation. Being used to full size headphones, I can never listen to the UM3X for too long, as I always feel that the music is restrained to a small box. The Baby Stax, on the other hand, plays the music in a big open space, and everything sounds much more alive and natural sounding in your brain. Not only is the music played on a much bigger space, each instruments are more distinguishable, possessing a much more distinct position in the soundstage.

stax_baby_1The Baby Stax may be a portable set up, but it’s a portable set up that needs to be babied. The cable is quite soft, and walking around with it, I always find myself watching over the fragile cable. The battery life is quite a pain, as alkalines only last short of 12 hours. It’s like owning a Ferrari. It’s a great automobile, but you have to literally baby the car (not the engine, though), bearing with all sorts of impracticalities and inconveniences. Yet at the end of the day, after you’ve heard the Baby Stax, you suddenly decide that you can live with all the nuisances.

Additional notes:
Some people mod the SRM-001 amplifier with better op-amps and better capacitors. You need to have some DIY electronics expertise to do this, but the results are well worth it. The default op-amps are quite poor, and the mods will give you a more extended highs and lows, adding detail as well as soundstage. In the process, often a heftier battery such as lithium ion is also fitted into the amplifier. The mods can be found if you google for “SuperFatCat Mod”.

Baby Stax
5 (100%) 1 vote

  • Jose


    How would you compare the UM Mage to these in terms of soundstage, treble extension and detail?

    • Hi Jose, the UM Mage is far superior in terms of soundstage, treble and bass extension, and detail when compared to the Baby Stax.

      • Jose

        Thanks for the fast response Mike!

  • stucker


    plz can you compare baby stax with w3 and um3x?

    and plz compare its soundstage to sennheiser ie8?


  • stucker

    sorry. my mistake. ignore w3 um3x :))

    plz only compare soundstage between baby stax and senn ie8?

    • Hey stucker, I guess you figured out the review on the $300 IEMs that includes the W3, UM3X, IE8, and the Baby Stax?
      Anyway, I'm talking from memory here, as I don't have them anymore. The IE8 has a big soundstage, but it doesn't feel open and natural. The Baby Stax, being the only open design IEM, feels more open and natural in the soundstage. I think the soundstage on the Baby Stax is one of its strongest points.

  • vidsan


    Based on sound quality alone (disregarding sound isolation, portability and durability), what are the baby Stax's IEM competitors in the same price range?

    • Well the Baby Stax sells for roughly $300, so that'll put it in the same range as the triple drivers universal IEM. It doesn't nearly have the detail level or extension of the balanced armature, but the sound signature is uniquely smooth and natural.

  • Mike

    It does sound nice, doesn't it? 🙂

  • Kanon

    Hi Mike, how do these compare to pk1/mx980/tm5? Is it worth the extra 200 over these?

    • Anonymous

      Detail level, the earbuds are better. Bass, the blox is better. The Stax
      is basically an electrostatic sound in the form of an IEM. But don’t
      expect much in terms of detail, extension, bass, soundstage imaging and
      such. It had a sweet midrange and is quite open sounding due to the open
      design though.

      It’s one of those things that are nice and interesting to own, but
      definitely not strong enough to stay as main earphone. In fact I’ll
      still take the ER4 over it, and I think most of the local baby Stax
      owners have gone back to the ER4 now. (to think that it was once dubbed
      the ultimate upgrade for ER4 owners — or something like that).

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  • Giuliana – CNDM

    Hi Mike,
    Do you know where can I buy cushions for the Stax SRM001? The cushions was lost, and know it is hurting people. Thank you

    • Sorry, your best bet is to contact Stax Japan