Hidizs S9 Pro Plus Martha English Review


Novelty Is Always A Plus




Construction and Design
Packaging and Accessories




  • Great sound quality/price ratio.
  • Enhanced aesthetics with a choice of three colours.
  • Robust, lightweight and stylish.
  • Volume buttons and selection of 6 sound filters.
  • High power through the 3.5mm SE output.
  • Low output impedance.
  • ASIO drivers.




  • The 3.5mm SE output connector is not gold-plated.
  • It heats up slightly when power is demanded.
  • It is not superior in all specifications to the S9 Pro.
  • As usual, the changes produced by the filters are for trained ears.


Purchase Link




1. Pre-order Starts: November 16th, 9:30 AM (EST)
    Ends: November 30th, 9:30 AM (EST)


2. Two Prices:


  • First 100 units 👉 $69.99
  •  After that 👉 $79.99


3. Shipping Date: December 5th, 2023


Exclusive 5% discount code:




The discount code will be available from 12:00 AM CST on November 15, 2023
And it is applicable to the first 100 orders as well.


Link to the WEB






Sometimes I think it’s amazing how portable audio brands from China are able to bring so many products to market. So far this year I have reviewed the IEMS MS5, MS3, MP145 and MS1. And now Hidizs is back with a revision of their famous S9 Pro dongle. However, they have not been very imaginative with the name of the new model: Hidizs S9 Pro Plus. Fortunately, they have been kind enough to add a codename: Martha. And this name was chosen «because «Martha» was the name of the last surviving female passenger pigeon, the largest species of flocking bird that ever existed on Earth. After 109 years since the extinction of the passenger pigeon, in commemoration of this magnificent species, professional acoustics brand Hidizs has chosen to name its third generation HiFi Balanced Dongle DAC, the S9 Pro Plus, after «Martha». S9 Pro Plus Martha adopts the fourth-generation professional HiFi audio processing circuit architecture developed by Hidizs Acoustic Laboratory. It is a fully balanced circuit architecture, consisting of four parts: USB interface processor, DAC, separate headphone amplifier and POP sound cancellation system. The DAC uses ESS Technology’s flagship ES9038Q2M DAC chip, which employs ESS Technology’s proprietary 32-bit HyperStream® II QUADDAC™ architecture and time-domain jitter eliminator. It guarantees the highest accuracy of audio data and represents the highest level of audio decoding technology. Its outstanding features make it the first choice for audiophiles and hi-fi music lovers. The ES9038Q2M chip supports a maximum PCM sampling rate of 32bit/768kHz, has an SNR of up to 128dB and an ultra-low THD+N of -120dB. It has two buttons to adjust the volume and to set up to 6 impulse response filters (PCM FILTER IMPULSE RESPONSE) by pressing both buttons at the same time. Each filter will be represented by a different colour. In reality, the big changes between the S9 Pro and S9 Pro Plus are aesthetic, the two volume buttons and the change of balanced output from 2.5mm to 4.4mm. Presumably there will also be an improvement in sound and specs. But we’ll get to that in this review.





  • DAC chip: ES9038Q2M
  • Headphone outputs: SE 3.5mm, BAL 4.4mm.
  • Frequency response: 20Hz-40kHz.
  • Distortion: PO (3.5mm): 0.0019%, BAL (4.4mm): 0.0008% (32Ω).
  • SNR: PO (3.5mm): 123dB, BAL (4.4mm): 120dB. (32Ω)
  • Separation: PO (3.5mm): 75dB, BAL (4.4mm): 115dB. (32Ω)
  • Output power: SE 3.5mm up to 138mW, BAL 4.4mm up to 180mW. (32Ω)
  • DSD: Native DSD64/128/256/512.
  • PCM: Support up to 768kHz/32Bit.
  • RGB LED sample rate indicator.
  • Volume control: 2 knobs.
  • Filters: 6 impulse response filters.
  • USB Type-C connection.
  • Weight: 17g.
  • Dimensions: 55x25x11mm.
  • Hi-Res Audio certified device.
  • Supported systems: Android, Windows, Mac OS, iPad OS, Harmony OS (to be compatible with iOS it is necessary to purchase separately a Lightning to Type-C cable with OTG function).
  • Choice of colours: Black, blue and silver.





Hidizs is once again repeating very similar packaging to its previous XO dongle. Martha comes in a very small, almost square, black box with dimensions 76x75x39mm. On the main side you can see a real picture of the S9 Pro Plus on a black background. At the top, on the left, is the model name as well as the description. At the bottom, also on the left, is the Hidizs logo. On the bottom right are the Hi-Res, DSD and ESS logos, all in holographic ink. On the back side are the specifications, both in English and Chinese, as well as other languages, in white ink. After removing the outer cardboard, a black plastic box appears, with the brand’s logo and slogan inscribed on the lid. On one side there is a sticker with the CE certificate. On the other side there is another sticker with the model name, between two linear barcodes. After opening the box the dongle is embedded in a foam mould lined with black cardboard. There is a strap to remove it. It is also protected by a cellophane bag. The complete contents are as follows:


  • The Hidizs S9 Pro Plus Martha dongle.
  • One short USB Type-C to Type-C cable.
  • One USB Type-C female to Type-A male adapter.
  • One warranty certificate.
  • One serial number card.
  • Two Hi-Res Audio stickers.


Again, the contents are as accurate and essential. There is no pouch to store the dongle, the USB cable is the same as always and the USB Type-C female to Type-A male adapter is still beautiful, practical and of high quality. A new Hidizs dongle under the same packaging and accessories. No need for innovation in this respect either.



Construction and Design


According to the specifications, the exterior of the S9 Pro Plus Martha is crafted from a single block of aerospace-grade aluminium using advanced CNC machining techniques. Both sides are protected by a glazed plastic plate. On the top face is the Hidizs logo. It is white, but translucent, below it is an RGB LED indicating the sample rates and filters. On the back side, on the top horizontal part is the ESS and DSD logo. Underneath it is indicated that it supports 32Bit/768kHz and DSD512. Finally, at the bottom is the full model name, all in silver ink.
Martha’s shape is not a simple rectangular lozenge. On the left side, it has a subtle upward slope. On the right side are the two buttons, equidistant from each other, on a side that decreases from the ends, similar to the opposite side. The decrease is in gradient, as in width, until it reaches the buttons. Both look like two small potentiometer wheels, because of the grooves around them. But these buttons do not rotate, they can only be pressed. Both the shape of the bezels around them and the grooves on their edge suggest the opposite. On the top side are the headphone sockets. The 3.5mm SE output has a black border while the 4.4mm output is gold-plated. At the bottom is the USB Type-C connector.
The dimensions are 55x25x11mm and it weighs 17 grams.
My model is blue, it is quite eye-catching and nice. It is a small device that warms up subtly. The bevelled details on the edges give it a distinctive, special and attractive touch. I like it, but it’s still a simple, minimalist yet elegant design. I would have liked the 3.5mm jack to be gold-plated as well.





The Hidizs S9 Pro Plus Martha is compatible with Android, Windows, Mac OS, iPad OS, Harmony OS. For iOS compatibility, a Lightning to Type-C cable with OTG function must be purchased separately. For Windows 10 and above no additional driver is required and ASIO driver is available. Allows exclusive mode with HiBy Music APP. It does not support microphone, but it can control the volume of the system by means of its two buttons.





The operability of the S9 Pro Plus is somewhat more comprehensive, due to its two buttons. Initially, the buttons were used to change songs. After a new firmware update, they adopted the volume functionality, which I consider much more practical and necessary. It also became ASIO compatible through the installation of a particular driver on my Windows 10. The two buttons also have another functionality: by pressing both at the same time you can change the filter. They are as follows and each has an assigned colour that flashes when selected:


  • Green light: Anodizing fast roll-off (Default filter): Voices are slightly advanced and high frequencies are extended with reduced resonance.
  • Red light: Linear phase fast roll-off: Enhanced analytical capabilities, offering a clean and crisp sound.
  • Blue light: Linear phase slow roll-off: Enriched harmonics, full low frequencies and natural reverberation.
  • Yellow light: Minimum phase fast roll-off: Balanced and moderate sound.
  • Purple light: Minimum phase slow roll-off: Clean sound with a forward position.
  • White light: Hybrid fast roll-off: Soft and smooth sound with enhanced detail.


It goes without saying that these filters also exist in other devices and are specific to the ESS DAC. Although I must confess that their impact on the sound is imperceptible to yours truly.On the other hand, as usual, the general purpose of the RGB LED is to indicate the sample rate or format played, according to the following table:


  • Yellow: DSD 64/128.
  • Purple: DSD 256/512.
  • Blue: PCM 176.4/192 kHz.
  • Red: PCM 352.8/384 kHz.
  • White: PCM 705.6/768 kHz.
  • Green: PCM 44.1/48/88.2/96 kHz.


My usual tests are with my PC using Foobar 2000 x64 with ASIO drivers. I have also tested it with Android and HiBy Music with the exclusive mode. The downside I have found with HiBy Music is that the hardware volume jumps controlled by the dongle are a bit big, there can be a higher change than desired. Another thing is that the volume is only changed if the APP is in the foreground.
In Windows 10 the volume control works from 0 to 100, but with 2-step jumps, as is usual with other volume-controlled dongles. Not bad.
Finally, it doesn’t have gain modes.





As can be seen in the specifications, Martha’s power is 138mW on SE and 180mW on BAL at 32Ω. In reality it is 150mW for both outputs, a little higher for SE, but a little lower for BAL. I have verified that it can give 2.76V per BAL at 33Ω with a pure tone of 5kHz, but I have not been able to make such a measurement with lower frequencies, simply, it is not able to give that power in all the frequency range. In that special case, the power would be 230mW, a very high value. And that means that Martha is capable of a lot.
The output impedance values are very good: 0.3Ω for the 3.5mm SE output and 0.5Ω for the 4.4mm BAL output. Here are some reference values.



No load SE


With no load on the 3.5mm output Martha reaches a value above 2V, more precisely 2.2V. Very good.



15Ω SE


1.222V for this impedance, 100mW and 81mA, great value.



33Ω SE


Martha is overmatched for this impedance: 2.2V, 150mW and 66mA. Excellent.



100Ω SE


Again the maximum value for a higher impedance: 2.2V, 49mW and 22mA.



No load BAL


With no load on the 4.4mm output Martha reaches 4.477V. Upper.





Martha has been chilled at this impedance by BAL, giving values lower than the SE output: 1V, 69mW and 68mA.





Once again it falters in BAL at 33Ω, it matches the values for SE: 2.2V, 150mW and 66mA, a bit far from the 180mW it promises. It would have been necessary to reach 2.4V, but it is very close.



100Ω BAL


Full output for this higher impedance: 4.453V, 200mW and 44mA. Very good.



Frequency Response


As can be seen in the graph, Martha has a flat response from 5Hz to 40kHz over the entire volume range. There is also no difference between channels, as both signals overlap. It is a Hi-Res device.





Hidizs again emphasises the use of Sabre’s ES9038Q2M DAC, which worked so well in the S9 Pro. Comparing the specifications, there doesn’t seem to be a clear winner. Martha wins in SNR, but in channel separation the S9 Pro is still ahead. It also has lower distortion on the 3.5mm output and more power per BAL. But the specs, when it comes to such high or low values, are very difficult to differentiate by ear and the suggestion may be more powerful. Be that as it may, I find Martha brings a point of delicacy over the already good sound of the previous S9 Pro. Starting with the low end, Martha awakens with a special control over the more extreme frequencies. The performance is slightly warm, compact, the bass performance is dry, fast and with a quick decay. It leaves no aftertaste and the texture is smooth, without being too rough. The bass is technical, deep, but not too dark, even then it is neutral. As it has very good resolution, it is able to follow bass lines perfectly and laminate layers with precision, thanks also to its great control, dryness and speed. All this makes the bass rich and descriptive, though perhaps lacking a little more punch or violence, given its education.
In the mid-range, its neutrality gives it transparency, a slight lightness, as well as a natural and realistic timbre, which does not lean to either side. There is a point of sharpness and grace, due to the clarity provided, which adds a more accentuated dynamic feel, allowing for a more moving and lively sound. In that way the vocals are vivacious and crisp, while the instrumentation is given a purposeful dynamism.
The treble follows the product’s tone and comes across as neutral and extended, in just the right amount, while maintaining a warmth and musical softness. They are never bright or uncontrolled. Part of Martha’s superior finesse is underpinned by the well-shaped, precise treble presentation, with great mastery of energy delivery, speed, resolution and definition. As a great Hi-Res product, Martha has a remarkable amount of air and hence that sense of clean, transparent sound. On the other hand, that distinguished point makes its sound more docile, consistent and controlled in complex and saturated situations. At this point it is able to bring order and generate a more polite and musical performance.
At the stage level, Martha has great laterality, generating a remarkable stereo feel and producing an oval presentation with a medium depth, quite in keeping with the overall size. There is a good sense of height, but no full or immersive three-dimensional recreation. There is a good amount of air and separation, while the background is discernible, without going to the extreme of blackness or pristine separation. Perhaps that is its limit and that is why the scene is natural, not overly volatile or gauzy, but rather realistic and relatively tight. The image and instrumental positioning is obvious and flawless, pleasant and understandable. The good lateral sensation allows the oval that extends up to 180°, which makes it possible for the elements to be separated, well distributed and rationally presented, easily distinguishable, being able to improve and scale with superior headphones.





Tempotec Sonata BHD Pro


Both dongles are recent, although the Tempotec has been on sale for a few weeks. Like Hidizs, Tempotec is sticking to its guns by using its CS43131 DAC in dual mode, adding a professional FPGA. Both have volume control, 3.5mm and 4.4mm outputs, RGB LEDs and a similar size. Both are metallic and the Tempotec stands out for its transparent window to the inside, while the Hidizs stands out for its more elegant design. The Tempotec has the possibility to change its sound via firmwares, while the Hidizs has 6 filters that can be changed by pressing the two buttons at the same time. The SNR of the Tempotec is higher, 131dB to 123dB and the distortion is lower, 0.00012% to 0.0008%. The Hidizs is more powerful, 150mW at 33Ω per BAL versus 100mW at 33Ω per BAL for the Tempotec. The Hidizs can play formats up to 768kHz/32Bit and DSD512, while the Tempotec goes up to 384kHz/32Bit and DSD256.
In terms of sound, the Tempotec is warmer, while the Hidizs is more neutral and somewhat more clean. Starting with the lower end, the Tempotec feels a little lower, with the sub-bass reproduction being deeper and darker. Its texture is rougher and the bass is bigger overall, taking up more volume and space, with a bit more power, even. On the other hand, the Hidizs is more neutral, compact, defined and fast, its transitions are quicker and it sounds drier, with higher control. The result is a cleaner bass, not as deep, not as dark, but with better technicalities.
In the middle area, the Hidizs is somewhat more transparent, although the level of detail is similar, the difference being in its representation. In this respect, the subtle warmth of the Tempotec is noticeable, being somewhat darker. Whereas Hidizs has slightly more luminosity. However, the Tempotec has a higher level of resolution when it comes to rendering details in the background of the scene, which go unnoticed. The Hidizs also reaches that point, but it is the detail that is the difference, that point of darkness and warmth in the Tempotec and that slight clarity in the Hidizs. In this way, the character of the Hidizs is subtly cleaner, with a little more sparkle. The Tempotec is more subdued, equally descriptive, but it is quieter, less striking because it is calmer and softer. That sparkle brings a liveliness to the Hidizs vocals and a little more dynamic feel to the instruments.
In the upper range, Hidizs has a behaviour that combines control, resolution and sparkle. Tempotec is quieter, with a slightly lower energy, but not as clean. The Hidizs is perceived as more loose and in noisier environments seems to reflect a more controlled, polished and resolute character, generating a more musical and less intricate response than the Tempotec.
The Hidisz’s soundstage seems more open, reaching a 180° oval, while the Tempotec is a little more clipped. Both sound quite crisp and separated, but I find a little more order and openness in the Hidizs, perhaps the mix of speed, refinement, control and dryness brings a more expansive point to its soundstage, with a little more light and separation. On the other hand, the Tempotec is a little rawer, a little more violent, which gives it more texture, a slower decay and a subtly more abrupt character than the Hidizs, but also with a little less separation and definition across the notes.





Hidizs presents the new S9 Pro Plus Martha as the logical evolution of its previous successful dongle S9 Pro. Continuing with the name, until the superlative suffixes run out, Hidizs wanted to give it a more human name. Martha incorporates two buttons to control volume and change filters, as well as replacing the balanced 2.5mm output with a more robust 4.4mm output. It retains the informative RGB LED and a restrained size, improving the aesthetics, increasing the beauty of the device. The power of the SE output has been increased, while the BAL output has been slightly decreased. Compared to the previous model, there is no clear winner in terms of specifications. However, Martha’s sound has gained in exquisiteness, being more distinguished and select. The new Hidizs dongle is characterised by a sound that is neutral, but soft, not bright, slightly warm, but not dark. But, without a doubt, one of Martha’s greatest assets is the sound quality for its price, being able to extract very good potential from the DAC used. There are more and more dongles on the market and choosing one is always difficult. Martha is among the most powerful I have tested in its price range and can play the most extreme formats such as DSD512 and PCM 768kHz/32Bit. It is also very versatile and compatible with multiple systems, robust and light enough for everyday use. All this makes it very easy to recommend.



Earphones and Sources Used During Analysis


  • Hidizs AP80 PRO-X Red Copper LE.
  • Xiaomi Redmi Note 8 Pro.
  • Hidizs MP145.
  • Hidizs MS5.
  • Hidizs MS3.
  • Kefine Klanar.
  • KiiBOOM Evoke.
  • Kiwi Ears Melody.
  • Letshuoer S15.