STAX SRM-D10
Headfonics 2019

Stax SRM-D10 First Contact

Marcus
First Contact

Disclaimer: The Stax SRM-D10 sent to us is a sample in exchange for our honest opinion. We thank the team at Stax for giving us this opportunity.

To read more about electrostatic products we reviewed on Headfonics click here.

This is our first formal Stax product review on Headfonics though we have done a fair few electrostatic product reviews down through the years. I first saw this in the run-up to CanJam Singapore 2018 so I ended up speaking to the guys at Stax and inquiring if we could work together on the SRM-D10 since the concept of a transportable amp for stats headphones has been a dream of mine.

Since then we had hoped to bring this First Contact and subsequent full review much earlier than this so apologies to anyone who was waiting on it.

The Story

Now to be fair, I have had a portable stats amp in our office before and it is right beside me, the Kingsound M-03. However, the SRM-D10 is both a DAC and an amp and specifically tuned for Stax headphones so this is a whole different angle for me. Stax is promoting this heavily as a first and looking around the market this still may well be the first and only such example.

My own opinion is that the electrostatics market has a somewhat conservative characteristic. Things tend to change at a much slower pace than the planar or dynamic headphone market and positively glacial compared to the in-ear sector.

I see that as a consequence of the way electrostatics work and the type of power they demand. Up until this point, most amps outside of the Baby Stax range are 100% desktop and at times quite large. No issues there is you are a stats fan and primarily a desktop user.

For those with smaller setups or maybe looking for something more discreet then the options are more limited. With the launch of the SRM-D10 at $899 (and the new D50 indirectly), those options just got a little wider.

Technology Inside

Amp

At its heart, this is a proper yet portable electrostatic amplifier with a 5-pin PRO bias Stax headphone output connector and a 200Vrms output rating under load.

DAC

However, it is more than that. It also packs a DAC inside, an ESS ES9018 DAC coupled with TI OPA1642. It is capable of hooking right up to your laptop and decoding up to DSD128 and PCM audio up to 384KHz. The D10 will also handle a line-in from another source as well as operating as a dedicated USB-DAC. Can it handle OTG based digital audio from your phone or DAP? Yes, it can!

Battery Powered

Oh, and one more thing. The D10 is fully transportable with a battery inside to allow you to unhook it from its DC connector (for charging). Now the numbers aren’t amazing. This is around 3-5 hours max playback time (in our testing around 4 hours) but you have to remember how much voltage is required to drive stats and its a lot more than IEMs. Combine that with a DAC and it feels about right.

That’s why I am initially calling it transportable rather than portable. Stats headphones are generally big and open so it is unlikely this setup will ever be seen as a commuter or gym solution.

STAX SRM-D10

Unboxing

The quality of the packaging is true to the Stax level of professionalism. It is not the smallest for what is, after all, a fairly compact device and you really have no idea what is inside with just the branding on the front of the box.

However, the layout is very tastefully done with a neat arrangement of four cardboard boxes of accessories in the bottom layer and the amp unit in a top layer of protective foam. The amp itself is protected with one of those old iPod style thin film wraps.

STAX SRM-D10

Accessories

Inside those neat little boxes, you get a DC 14V switching charger, 2 sets of USB cables (one right-angled), a short 3.5mm interconnect for analog and a bunch of charger adapters for whatever sockets you happen to have in your part of the world. The third box in the pic above is your usual assortment of manuals, guide and warranty details.

STAX SRM-D10

Build Quality

Our initial impressions of the D10 is a fairly hefty device at 450g but one that is beautifully engineered. Certainly, the design is much more complex and premium to look at and hold than the fairly cheap looking Kingsound M-03 alternative.

STAX SRM-D10

The materials are all-aluminum and look to be a 3-piece design with the main body, front panel with rotary dial guard, and a rear panel. Screws are little obvious on the sides, not terribly discreet but not a deal breaker either. They sit slight inset so they won’t catch anything accidentally.

The finish is just excellent. The silver anodized paint job sits over this grooved top panel that provides a good level of grip in the hand. The 450g weight really does require it not to be slippy and the D10 is not slippy at all. It does, however, get a bit warm during use.

Inputs & Outputs

To the front things are fairly simple with a 5-pin pro bias female socket and smooth and grippy rotary volume dial. The dial is set slightly in with protection to the left and right to prevent accidental volume bumps. It also doubles as resistance-based power on and off dial. By the way, much of the D10’s thickness is more of a limitation of the pro bias socket’s dimensions. It is quite large and unlikely to change for the foreseeable future.

STAX SRM-D10

To the rear of the D10, it gets a lot busier. Here you will find the DC input for the charger, a USB/Line-in switch for analog or digital input selection and a micro USB socket for digital audio purposes. The line-in socket to the far left completes the line-up.

STAX SRM-D10

It is a pity Stax didn’t opt for USB-C for their digital socket and introduce some fast charging element to the devices power supply and keep it future-proofed. Having said that micro-USB is still fine for most situations and there are plenty of cheap USB-C adapters if you really need one.

STAX SRM-D10

Initial Sound Impressions

(Tested with a PC/Foobar 44.1k 16BIT FLAC tracks as well as a HiBy Music R6 Pro DAP as an analog source with a 2V line-out)

My initial impression of the D10 is of a reasonably clean and relatively transparent or neutral sounding amp with nothing in the way of any harsh Sabre glare, at least not with the MrSpeakers VOCE and Stax’s own 007 MK2. The dynamic range is good and the resolution is better than I expected with pretty much any stats headphone we used.

For power, the VOCE seems to push the D10 quite hard in terms of current and subsequently, I found myself looking for a little more headroom than I think it can deliver. The VOCE is much harder to drive than the 007 MK2 or the ESP950 so this may well be the exception than the norm for the D10.

For the Stax 007 MK2, which is the easier of the two headphones to drive, there are no issues with a max comfortable volume range for me around 1pm on the dial.

STAX SRM-D10

Vs Kingsound M-03

My initial comparisons with the Kingsound M-03 are favorable in most areas except power where I think the M-03 might have an edge with more demanding stats headphones. Though by no means a liquid sounding DAC, the D10 does sound smoother and more refined than the M-03, especially its treble which is little edgier and brighter on the M-03.

Of course, the M-03 is just an amp so it is somewhat source dependent and you can adjust that sound from an EQ or DSP point of view. With the R6 Pro DAP using its line-out the Kingsound sounded punchier in the low-end than the D10 for instance.

You can also bypass the DAC section of the D10 also using either its analog line-in or the USB port and produce a similar effect. Here, the D10 steps ahead with a more refined treble delivery using the R6 Pro as a test case source. I think in the full review we will explore higher-end DACs such as the Hugo 2 and Qutest just to see how well the D10 amp stage can really perform.

STAX SRM-D10

Stay Tuned!

I am really batting for the SRM-D10 on a personal preference level, to be honest with you. I just hope it can live up to my excited expectations in the main review. There are some slight concerns on just how much power this can deliver to the likes of the VOCE and just how good an ES9018 chipset really is for highly resolving headphones in 2019.

However, its Stax, it is portable and it already sounds and looks more refined than the only other portable stats amp I have heard to date, the Kingsound M-03. The fact that I can connect it to other DACs is an exciting option so for the main review, you can expect to see plenty of matchups and not just as a USB-DAC for the PC. There is a lot of potential here so stay tuned!

Stax SRM-D10 Specifications

  • 5-pin PRO bias Stax earspeaker output
  • MicroUSB digital input,
  • 3.5mm analog input
  • Supply voltage: DC 14V (charger included)
  • Frequency response: 20Hz – 40KHz (+0dB,-3dB)
  • Rated input level: 230mV (100V output)
  • Harmonic distortion: <0.025% / 1KHz-10KHz
  • Input impedance: 10 KΩ (analog input)
  • Maximum output voltage: 200Vr.m.s / 100Hz-10KHz
  • Power consumption: 6.4W (USB input) 5W (analog input)
  • Recommended operating temperature: 0-35°C, <90% RH (No condensation)
  • Dimensions: 75(W) X 32(H) X 141(D) mm
  • Net weight: 450g
  • Voltage: 100-240V/50-60HZ
  • Warranty: 1-year U.S. limited warranty

 

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Marcus
Editor
Marcus is the Founder & Owner of headfonics.com which started in 2011, and a former contributing music journalist to European regional printed newspapers in the late 1980's and 1990's. Prior to the start of Headfonics Marcus was the admin of the Headphiles national audiophile forum from 2009 to 2012.

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18 Responses

  2. I have the Stax SR-L300 with the SRM-252S Energizer (beginner setup). From what I’ve read, the L300 sounds about the same as the more comfortable L-500 (L700 is out of my league). The SRM-252 has a good Class A amp. I have no need for more D/A Converters. My Input to the SRM-252 is from SACD sources and Qobuz hi res classical streaming directly from a Bluesound Node 2i.

    I want the best audio possible for my budget. I could squeeze in a D-10 if I would gain more profound audio yet. But for all I know they used the same amp in the D-10 as in the SRM-252 and just added D/A converters and a fancier package.

    With upgrade I would hope to gain punchier bass, more depth, and a broader yet soundstage. I’m transitioning from a fairly heavyweight Magneplanar speaker system (purchased before retirement, social security, and age related difficulty in getting behind that massive mess to switch cabling around to fit my mood.).

    As always, my first test is with Miles Davis Sketches of Spain. With this Stax arrangement, these headphones passed with flying colors with all instruments heard distinctly, clearly, crisply, and with excellent. stage.

    Do you have any recommendations?

    P.S. I’m also looking at the SRM D-50 as a possibility (a couple of hundred bucks more).

    1. That’s a lot of possibilities but I do not have the 300 or 500 or the SRM-252 or the D50 so I cannot see myself being to offer much insight in this case.

      What I use by way of Stax is an L-300 Limited edition with 700 drivers inside, an old 3030 headphone plus amp system plus an 007 MKII with the D10 for light use, and an SRM-007tII energizer to drive the main system from an R2R DAC.

      I do have a buddy who swears by the D10 with a 009s which to me might be a bright system. I prefer mellow and tubes and a bit more bass thats why I opted for the 007 MKII. Still, my buddy runs an audio store so he might know a thing or two. Me, I like the L-300 SE with the D10, easy enough to drive and excellent resolution – that might be a good marker.

  3. Hi Marcus, my current set up is the D-10 with L700s and have wondered if the ESS ES9018 DAC dac chip found in the D-10 needs to be upgraded with an external dac? The ESS9018 was one of the best back when Stax first introduced the D-10 but as technology doesn’t stand still for anyone, I was wondering if a replacement external dac should be explored? If yes and keeping in mind the collective cost of my set up and abilities, can you recommended one or two possibilities? As always I enjoy your articles and look forward to your response. Thank you for this consideration. Dean

    1. I honestly think the biggest upgrade is moving to an e-stats tube amp rather than upgrading the DAC. Often the biggest increase in performance is the amp stage as opposed to the DAC and in the case of the D10 its not the most powerful for me.

      1. Thank you. Micheal over at Woo Audio/Stax USA had the same advice. Suggested his WES at the $4500 level. Boy, E/Stat tube amps sure can be pricey!

  4. Hi,

    Will you ever touch the unit second time for a review? No progress since a long time.

    Cheers

    1. Sure we will though we had to send it in for a small repair due to a minor accident lol, but in the meantime is there anything specific you wanted to know?

  5. Should the unit be left on charger all the time or just when needed to replenish a charge back to full from empty? My concern is not to shorten the life of the battery by having it on full charge all the time as this in some cases can shorten charge capacity.
    Thank you, Dean

    1. I think to treat it like a laptop battery and how you use that. I tend to leave that in a few days, then take it out, run down the battery and then charge it up again.

      1. Marcus,
        Thank you. Any harm done to listen to the D-10 while charger connected? Either sonically or damaging to the lithium batteries themselves? I’m pretty sure DC will sound better than AC but with run times of 3 to 4 hour do I do harm to the batteries if I listen while the unit is plugged into the wall and drawing power simultaneously? I appreciate your taking my questions, very little is found about this amp/dac online or even from Stax. Regards.

        1. I can’t see it being an issue and that’s how I use it most of the time. I would just treat it like a regular battery usage case and charge it down now and then and not keep it always on the ac and full battery.

  6. Very sloppy editing, you’d think you could spell the product name correctly? Stax not Stats…. and more than once!

    1. James that is the incorrect interpretation of the word stats. It is short for electrostatic and not a typo of Stax.

      For example, a stats amp is an electrostatic amp but necessarily of the brand Stax.

  7. A micro USB? Deal breaker. While Stax makes good stuff, they do have a habit of not exactly thinking things through in terms of long term reliability.

    1. Well, I have always felt things move slowly in the electrostatic world and a micro USB connection would reflect that. From your point of view how does it become a deal breaker?

      1. Not robust, they break easily; quality USB cables are rarely available terminated with them. At least USB C would have made sense.

    2. For me on the OTG aspect micro USB is more prevalent to buy than micro USB-C right now though I hope that changes in due course.

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