The Magic Clip
- Above all, sound quality.
- Balanced 4V RMS output, in addition to the classic 3.5mm.
- APP control, totally comprehensive, robust, yet simple and very well explained, from the screens themselves.
- Very low weight.
- Easy to use.
- Reduced size.
- Logical operation of the buttons.
- Graphic and parametric equalizer, 10 bands.
- Very high sound quality via Bluetooth.
- Huge amount of configuration options.
- Battery life.
- USB DAC limited to 24-bit/96kHz, does not play DSD
- No ASIO drivers.
- Cables are rigid.
- 3.5mm output limited to single DAC use.
- No case to protect it during transport.
THZC Trading Limited Hongkong:
XChesser Audio Russia:
Link to the Store
Qudelix, as highlighted on its website, is an audio systems engineering company, based in Seoul, Korea. They are also a technical partner of Sony LDAC™. They have developed the LDAC solution for the Qualcomm QCC512X platform, which is one of the best chips for audio playback via Bluetooth. This platform, besides offering the best quality codec for Bluetooth audio, has an ultra low power consumption. On the other hand, it has a powerful DSP, capable of maintaining a high bitrate during transmission, in a safer way and for longer. As a result of this effort, Qudelix provides such LDAC codec solution to other brands and/or headphone manufacturers.
All this technical capacity has resulted in one of the most interesting devices on the portable Hi-End market, which combines the best Bluetooth option, with an excellent Dual DAC/AMP by SABRE (ES9218P) and a high output power. This is the Qudelix-5K: a small Bluetooth receiver of very high quality and a DAC/AMP. It can be used as a sound card, connected to a PC or laptop. It can also be connected, via Bluetooth, to a Smartphone or DAP, to be used as a Bluetooth receiver and headphone amplifier. Finally, it can also be connected, via USB-C, to a Smartphone or DAP, to be used as an amplifier. It even has a high-sensitivity microphone as a Bluetooth communication solution.
It has 3.5mm (80mW to 32Ω) and balanced 2.5mm (240mW to 32Ω) outputs.
Another great advantage of this small device (it only weighs 25g) is that it can be governed, completely, by way of an attractive APP, which can be downloaded from the official Google and Apple shops:
It is very easy to use and is capable of getting the most out of the 5K, controlling the volume, output, codecs used, power supplied, sound quality… it even has a graphic and parametric equalizer, 10 bands, which works, even if the source is Bluetooth.
In the present review, I’m going to go through all the details of this versatile and very complete product.
- Maximum output power 3.5mm Unbalanced: 2.0V RMS (80mW per channel)
- Maximum output power 2.5mm balanced output: 4.0V RMS (240mW per channel)
- SNR (A-weighted): 3.5mm -118dB. 2.5mm -122dB
- THD+N: 3.5mm 0.004%. 2.5mm 0.002%.
- Separation: 3.5mm 79dB. 2.5mm 117dB (1kHz/32Ω).
- Output impedance: <1Ω.
- Bluetooth: 5.0 Class 2 (25mW 4dBm) up to 10m. 2.4Ghz.
- Bluetooth chip: Qualcomm QCC5124
- DAC: Dual ES9218P SABRE HiFi®. The 3.5mm output works in single DAC, only. Dual DAC is only available for 2.5mm output.
- Bluetooth Codecs: aptX Adaptive, LDAC, AAC, aptX-HD, aptX, SBC
- Battery life: 6 to 20 hours (500mA Battery)
- Use as USB DAC: maximum resolution 96KHz/24-bit
- Double Precision 10 Band Equalizer PEQ/GEQ
- LDS (Laser Direct Structuring) antenna, high sensitivity and 3 dimensions.
- Technology used for noise cancellation: Qualcomm® cVc™
- Microphone: High sensitivity MEMS.
- Firmware update via Over-the-Air (OTA).
- Complementary mobile application iOS/Android.
Surprisingly, the Qudelix-5k comes in a small, unpainted, pure cardboard box. Its dimensions are 91x55x55mm. It is sealed with two transparent stickers, on the top and bottom. On the different sides of the box, there are different notes on the product. On the upper side is the brand name, logo, slogan, where it was manufactured (Korea) and the different guarantee certificates. On the lower side there is an EAN13 code. On the other sides, there are drawings of each side of the product, explaining its basic functions, as a quick guide.
After opening the box, on the upper side, you can see the DAC, wrapped in a bubble bag, located in an area adjusted to its size. If you open it from the bottom, you will find a zip bag containing two black cables. One is a USB-C to USB-C type and the other is a USB to USB-C type. They are all male. The full length, including connectors, of each one is approximately 150mm. And that’s it, no instruction manual or warranty card is included. On the other hand, the user’s manual and the operation note, can be downloaded through the APP or with the existing links on their website (which I have previously linked). These documents are very complete and excellently explained.
The guarantee is for one year and their condition can be checked through the APP.
The content, as you can see, is the minimum required. The packaging feels like an industrial, rather than a commercial product. However, it does not cease to have its charm. The box and its design, through a single sheet of untreated cardboard, its drawings in black ink and its schematic explanations, give an idea of a different product, where the effort is inside and not in other less superfluous things. In any case, I like very much, that austere, simple but ingenious presentation and so reduced in size.
Construction and Design
The Qudelix-5K is a small regular parallelepiped, measuring 52.8×26.7×15.6mm. Its weight is 25g. Its body is made of very hard black plastic. It also has an anti-scratch UV coating. It has a dark grey aluminium clip at its base. On it are written, in white ink, the model, where it has been manufactured, as well as the different certifications that it complies with. In a vertical position, on the upper face, the one that is closest to the clamp’s ball joint, are the audio outputs, 3.5mm and 2.5mm (balanced), as well as a hole for the microphone. On the opposite side is the USB-C connection. On the left side, there is a button with a double function: if you press on its top, the volume increases. After pressing the lower part, it is lowered. It is translucent and lights up in red with each press. On the left side, there is another button, with the difference that it has a bulge at the top, to make it easier to identify by touch. On this occasion, its light is blue. Pressing the upper part for 3 seconds, you enter Bluetooth pairing mode. Pressing the bottom part, also for 3 seconds, turns it off or on, as appropriate. Finally, at the base of the front panel, you can read «qudelix» in inscribed letters.
Despite the fact that the body is made of plastic, with the exception of the clamp, its high rigidity gives a rather hard feeling. Even, with the paint, it seems that its body is completely metallic.
Its construction is extremely compact, only two screws can be seen on the face where the USB connection is. Although, it is possible to see the slots and joints, these are either very small or are very well assembled and do not offer any sensation of weakness. Despite the simplicity of the form, the device has a very effective and functional design, more than striking or spectacular. Above all, its small size, weight (I repeat, 25g), as well as its efficient ergonomics and ease of use, stand out.
The 5K has two basic functions:
First, as a Bluetooth receiver/headset amplifier: in this case it will be necessary to connect to a Bluetooth source. The audio codecs used are SBC, AAC, aptX, aptX HD, aptX Adaptive and Sony LDAC™. In this regard, it should be noted that Qudelix, is Sony’s LDAC «Official Technical Partner» and has developed the LDAC solution for Qualcomm’s QCC512x platform, which is a best-in-class SoC for high-end Bluetooth applications. The QCC512x’s ultra-low power consumption and more powerful DSP capability allows application devices to maintain a more secure, high-bit-rate LDAC stream for longer. All this information is explained in detail on the brand’s own website. It should be noted, of course, that the 5K is the first LDAC receiver to display the active LDAC bit rate.
Second, as a USB DAC/headphone amplifier: the 5K can be connected, via the built-in USB cables, to a PC, a smartphone or a DAP with a compatible USB-C output. In this connection mode, the 5K supports the following sampling rates: 44.1/48/88.2/96kHz. Using the APP, you can choose a single rate or all of them. The bit depth is 24.
Connected to a PC, no drivers are required. For configuration, e.g. with Foobar2000, it will be necessary to choose the «WASAPI» (push) or (event) output and 24-bit. It can also be used with ASIO4ALL.
When connected to a smartphone, it is necessary to choose, in the playback APP, that the audio output be through the Qudelix-5K.
It should be noted that both connections can be established at the same time. The 5K can be connected to the Smartphone, either via Bluetooth or USB. The audio source can be chosen at any time via the playback APP or the Smartphone itself. When this is chosen, it becomes exclusive.
It can also be connected via Bluetooth, through the Smartphone and connected as a USB DAC to a PC. In this case, the Bluetooth source is the main source and the USB DAC connection is the secondary source. Simply by pausing one source and resuming the other, it is sufficient to switch the audio from each source.
The Qudelix-5K has two audio outputs, one 3.5mm and one 2.5mm balanced. The 3.5mm output offers an output voltage of 1V or 2V, selectable through the APP. Using this output, the 5K works in Single DAC mode.
The 2.5mm output offers 2V or 4V, also selectable through the APP. If this output is used, the 5K offers its best technical virtues, as it uses the Dual DAC configuration.
When the high power output is selected, the volume is not increased, but extended to +6dB, instead of 0dB.
The 5K has two profiles or modes: Standard or Performance. The Standard mode provides the best balance between sound quality and battery consumption. Basically, this mode uses the standard operating clock of the DAC and the standard output bias current. The Performance mode gives priority to sound quality as opposed to battery consumption, which may be shorter. In this case, the DAC clock works in its maximum position and the bias current is also the highest.
If connected as a USB DAC, the mode automatically switches to Performance mode, even if the Standard mode is selected.
The Qudelix-5K is an extremely versatile product. In addition to the above, connected via Bluetooth to the Smartphone, the high-sensitivity MEMS microphone can be used, which is built in. In this way, it is not necessary for the connected headphones to have a microphone. However, by means of the APP, it is possible to select the use of one or the other, including the sensitivity level, if the 5K microphone is used.
The operation of the 5k, is quite simple, it has 4 buttons, grouped one on each side, under a transparent casing. Each of them has an LED: blue for the right side (which also has a protruding mark on the top), red for the left. As a quick summary, their functionalities are:
Upper blue button:
- Pairing mode (long press 3 seconds)
- Play/pause (one click).
- Next song (double click).
- Answer incoming call (one click)
Lower blue button:
- On/off (long press 3 seconds).
- Previous song (double click).
Upper red button:
- Volume up (+0.5dB)
Lower red button:
- Volume down (-0.5dB)
To pair the 5K via Bluetooth, simply turn on the device and enter pairing mode. At this point, the red light and the blue light come on alternately to indicate this status. It is recommended that LDAC mode is chosen from the Smartphone, for maximum sound quality.
It is also possible, from the development options, in Android, to select the LDAC bitrate. The 990kbps/909kbps, 660kbps/606kbps, 330kbps/303kbps modes as well as the adaptive bitrate mode are supported and can be used. Even the used bitrate can be displayed from the APP.
The Bluetooth range is up to 10m.
The volume has an option, called «Absolute volume», which allows total control of the volume, both of the source (Smartphone) and of the 5K. This allows for fine adjustment and the best possible sound quality. The sound jumps of the device are measured in 0.5dB, obtaining a very high precision, as well as being simple to operate. The maximum volume is 0dB, but when the high gain is set, the maximum is +6dB, which means doubling the amount of volume.
The 5K, on the other hand, has a high volume protection, which protects the connected headphones, when switching between different audio sources. If the volume differences between them are too great, the system adjusts the volume as a protective measure.
The APP can also be used to limit the maximum volume as well as the volume of each channel.
As is usual with many DACs, it is possible to select between different filters. They are as follows:
- Linear phase fast roll-off.
- Linear phase slow roll-off.
- Minimum phase fast roll-off.
- Minimum phase slow roll-off.
- Apodizing fast roll-off type 1.
- Apodizing fast roll-off type 2.
- Hybrid fast roll-off.
- Brick Wall.
They can be chosen from the PPP and there are explanatory charts for each one.
The 5K has a 10-band equalizer. Thanks to the use of the QCC5124, which is the neurological centre of the device, it is possible to use such advanced audio processing. Inside is a 32-bit dual-core KALIMBA DSP, which runs at 120MHz. The use of the equalizer is independent of the source used, whether Bluetooth or USB.
The equalizer can be used parametrically (PEQ) or graphically (GEQ). Its equalisation processing is 64bits, with double precision.
It has a large number of pre-set presets and up to 10 individual presets can be saved. All of them are stored in the device’s flash memory.
It should be noted that the current status of the device is also stored in the internal memory and when it is switched on again, the system remembers this status.
The battery of the 5K, is 500mA, from Li-Polymer. Only a current of 200mA is required to charge it, a current which limits the device itself. This means that the entire charge takes 2.5 hours (pure and simple mathematics). The included battery charger can be activated at will, except when the battery charge is less than 20%, in which case it will be activated automatically, provided it is connected to a USB.
Connected as a USB DAC, the device uses 200mA for charging, if enabled, and 300mA for operation.
The power mode can be configured, among 4 options: Do nothing, turn on when connected as USB DAC, turn off when charging or turn on or off depending on whether or not it is connected to the charger. All these options can be chosen from the APP.
The battery life can vary between 6.71 hours (Performance mode, Balanced 4V LDAC 96kHz @990kbps) and 20 hours (Standard mode, Unbalanced 1V AAC 44.1kHz) depending on the tests performed in the laboratory.
As usual, the battery life will depend on each individual use, the volume used, the mode, the gain, the codec used and the transfer rate.
My experience of use, based on 70% connected as a USB DAC with the charger switched off and 30% via Bluetooth or connected to a DAP or Smartphone, via USB-C, is that the battery life is, practically, as the tests promise. After two weeks of daily use (1 to 4 hours a day), I have reached 20% battery life. It’s true that the connected headphones have been low impedance IEMS or low or medium impedance earbuds. I have alternated use, both by balanced and unbalanced output, switching between high and low gain. In addition, the 5K can be connected to the PC as a USB DAC and when not in use the battery consumption is minimal.
Finally, from the APP, there is a specific section to monitor the use of the battery.
As I have already insisted, the use of the Qudelix-5K is extremely simple. And the maturity of the APP makes it very easy to have absolute control of the device, and also provides a lot of information: help, links to manuals, to the forum, technical support, warranty management… It also allows the firmware to be updated, through OTA.
The version of the APP used during the writing of this review has been v1.5 and the firmware v1.3.2.
The APP works very smoothly and I have not detected any hang ups or abnormal functioning.
It has 5 large sections and within each section, there are several sub-sections. In summary, the distribution would be something like this:
In addition to the options, each screen has detailed information about each of them.
Personally, I love the theme with black background used, with the text in a soft white and the options selected in red.
One of the most interesting things about this device is its multifunction: it can be connected to the PC at the same time, via USB, as a DAC and connected to the Smartphone, via Bluetooth. All this, while having complete control, by means of the APP. You can listen to music via the smartphone, pause playback and resume playback on the PC, without having to touch the device or the APP at all.
To go into detail about the functioning of the PPP would be excessive for this review. So I prefer to put screenshots of practically all the screens, grouped in groups of 4 screenshots per image. The text is completely in English.
But I would like to mention some virtues and/or curiosities, related to the PPP and the configuration of the device:
The operation of the buttons can be programmed, offering alternatives of use to the pre-set one.
You can control the activation of the 5K microphone, as well as its gain level or choose to use the headset microphone.
It has a guarantee control, specifying the days remaining until the end of the period.
You can choose how the device works, when connected as a USB DAC or to a charger.
You can control the volume of the Smartphone, the device and display the Bluetooth codec being used, as well as its bitrate and transfer speed.
The equalizer can be used even if the selected source is Bluetooth.
All measures have been taken with the Performance option activated. The voltage measurements are RMS.
In the following table the 3.5mm output voltage has been measured (selecting the «Normal» or «High» option) with a digital multimeter, using a sine wave of 100Hz and amplitude 1, in FLAC 870kbps to 96kHz.
In the following table the voltage of the 2.5mm balanced output has been measured (selecting the option «Normal» or «High») with a digital multimeter, using a sine wave of 100Hz and amplitude 1, in FLAC 870kbps to 96kHz.
It can be seen that, at 32Ω, the output voltage does not reach the maximum. It is possible that at low impedance, the amplifier will reach current saturation. It should be remembered that, in the specifications, the maximum power is:
In order to visualize the pure waves, reproduced by the 5K, I used the oscilloscope.
The 3.5mm output, connected to 32Ω at 0dB volume, offers a slight saturation, at 1.06V.
The 3.5mm output, connected to 32Ω at -0.5dB volume, is unsaturated, at 1V. This means a power of 31.25mW.
The 3.5mm output, connected to 32Ω at 6dB volume, offers visible saturation, at 2.07V.
The 3.5mm output, connected to 32Ω at 5dB volume, has no saturation, at 1.85V. This indicates that the power of the unbalanced output is 110mW, higher than the 80mW declared. The current required to obtain this power is 57mA.
The 3.5mm output, connected to 100Ω at 6dB volume, does not present saturation, at 2.1V. The power measured at this point is 44.1mW.
The 2.5mm output, connected to 32Ω at 0dB volume, has a clear saturation, at 1.79V.
The 2.5mm output, connected to 32Ω at -2dB volume, has no saturation, at 1.68V. The power at this point is 88.2mW.
The 2.5mm output connected to 32Ω at 6dB volume, has a clear saturation at 3.22V.
The 2.5mm output, connected to 32Ω at 3dB volume, provides a clean signal, at 2.92V. The power measured at this point is 270mW, which is more than the 240mW declared. The current in this case is 91mA.
The 2.5mm output, connected to 100Ω at 0dB volume, has no saturation, at 2.14V.
The 2.5mm output, connected to 100Ω at 6dB volume, has no saturation, at 4.13mW, and the power is 170mW.
It can be seen, then, in spite of the visual measurements, that the Qudelix-5K, for the 3.5mm output, at 32Ω, offers more power than stated (110mW), clearly exceeding the 80mW indicated in the specifications.
Something similar happens with the 2.5mm output, capable of reaching 270mW, for 32Ω, which is a great power figure, higher than the 240mW declared.
In the following picture you can see the frequency response, from 5Hz to 40kHz. You can see that the response is completely flat, from 20Hz to 30kHz:
Finally, below are the measurements taken with the oscilloscope, without load, making a frequency scan, from 20Hz to 20kHz, using the maximum volume (0db and 6dB), for both outputs.
3.5mm Output at 1V:
3.5mm Output at 2V:
2.5mm Output at 2V:
2.5mm Output at 4V:
Thanks to the ability to connect to multiple sources at once (Bluetooth and USB DAC), it is easy to switch quickly between them, just by pausing one and resuming the other. In this way it is very easy to make comparisons between the two connections. The fundamental conclusion is that there are hardly any differences between the two sources. With medium or low range headphones and MP3 files at 320 Kbps, I would dare to say that the differences are almost indistinguishable. If I were to carry out blind tests, playing the same files, I don’t think I would be able to distinguish either the differences or the origin of the source. This is something that has really surprised me. With the Qudelix-5K it is no longer necessary to have a DAP, if our Smartphone has LDAC and a sampling rate of 660kbps, or more, it is totally sufficient. And it doesn’t matter if it has been tested for the 3.5mm or the 2.5mm output.
To find some differences you would have to go to great files, very well recorded music and use the best headphones you have. But even so, the results are very similar, bearing in mind the limitation that, by USB, you can only play files of up to 96kHz (a value which, on the other hand, is quite high). My feeling is that, via USB, there is a greater sense of dynamics and that the recreation of the scene is more rounded, with greater depth and three-dimensional effect. But the extraction of detail and the presentation of the sound are really on a par.
Speaking purely of sound, the profile of the Qudelix-5K is quite neutral, I don’t find it to be an amplifier, either warm, dark or overly bright. Its balance is perfect for respecting the signature of the connected headphones. In this sense, you can notice that the DACs used are SABRE, where the quality of the details and the resolution capacity are quite exposed. On the other hand, I think that the 5K is not completely analytical, but it is true that it has quite an inclination towards that profile, more than another declared soft. In my case, this type of sound is very much in line with my preferences, which is why, from the very first moment, the device has taken over most of the time, as an audio player, on my desk.
The reproduction of the lower area is perceived as extremely clean, very well shaped, with a good resolution drawing, but without too much roughness, showing that more analytical and defined presentation. The depth is good and the separation of planes is on a par. But, really, it is not an amplifier that enhances the bass or gives it a higher weight than other bands. The balance it has is very noticeable, as well as the respect for executing the area with greater resolution, allowing its background to be quite clean and airy, achieving a fairly decongested and luminous sound.
These qualities benefit greatly from the needs of the mid-range. I do not understand that the 5K is a mid-center amplifier, but its characteristics are capable of enhancing the details and nuances of both the voices and the instruments. Its dark background, above all because it is balanced, gives great dynamics to the sound, as well as definition, transparency and quite high resolution capacity. Thus, the voices appear very natural and very well defined, accompanied by the perfect distance, between the accompanying instruments.
I find that one of the best qualities of the 5K is the respect it has for the sound of the connected headphones. It is very capable of extracting many of the virtues of each one of them, but in a very natural way, without the sound feeling forced or artificial. Its high resolution capacity offers a calm listening. Its level of definition does not overwhelm at all. And a good reason for this is the treatment it offers to the treble, drawing them very well exposed, thin, sharp, brilliant, but docile, with a definition at the height of the neutrality offered, accompanied by a large dose of air and separation. From this, we obtain that declared analytic character and its level of separation, which, in sum, is capable of generating a scene of appreciable width, remarkable depth and adequate height. The level of three-dimensionality is not very high, since the stage is observed from the front. But, in this way, the scene persists naturally, escaping any forced unreality.
Sabaj DA3, Tempotec Serenade iDSD
A three-way comparison between different devices, but of the same price, may be somewhat inconsistent. But, speaking purely of sound, it is totally justified.
Used, all, as USB DACs, the profiles differ between the iDSD and the 5K and DA3. The first is eminently warm, while the other two are more neutral.
Continuing with iDSD, it has the darkest sound of the three, with a more subtle brightness, where details are less exposed. Its sound feels more congested and cohesive, less clean.
The DA3 is harder, its edges are sharper, it’s almost the opposite of iDSD. It doesn’t have its softness, nor is it as wide, which enhances the feeling of a sharper, even more shrill profile. It has a higher resolution, but its sound lacks the finesse to respect the nuances, in a more polite way, without losing an ounce of the extracted information.
The 5K, stays in the middle, although closer to the profile of the DA3, but clearly improving the resolution level, the cleanliness of the sound and the delicacy of the reproduction. The DA3, however, can be unsettling because of its more punchy sound; with the 5K, you don’t get the same feeling. The sound is analytical, but delicate, executed with calm, light, definition and a lot of sharpness. In this way, the notes are appreciated more separated, with more air. The result is bigger, as well as pleasant and not at all tiring. The scene looks bigger than its competitors, with a higher level of three-dimensionality, easily one step above the other two. It can be seen that, the sound is more mature and refined, with more dynamics and transparency, which gives it a more absolute neutrality, allowing a more prolonged use, without neglecting the pleasure that causes its analytical capacity, totally peaceful and calm.
I do not have this model, but being its maximum potential rival, I think it is interesting to attach its differences, shown in the following image with the comparative table:
I haven’t been this excited about an audio device in a long time. This lightweight device has stolen my audiophile heart, from the very first note. I would say more, since the first Bluetooth wave. I must confess that I am a sceptic of Bluetooth: I think there could be better data transmission alternatives, with higher bandwidth, better bit rate and speed. Bluetooth has been extended and stretched, to meet some needs, based on a specification that, initially, was not intended for such use, at least with great quality. But then, comes that codec, called LDAC and the implementation of Qudelix, based on the Qualcomm QCC512X platform. And here, is where things change. With the 5K, I was able to combine USB and Bluetooth sources immediately. In this way, it’s very easy to look for the 7 differences… or rather, not find any. This has been the myth that has demolished the 5K: the shortcomings of Bluetooth are not in the specification, but in the codec and the subsequent amplification. And that is where Qudelix has embroidered it: it does not matter where the music comes from because its quality is practically the same. And I’m not talking about average quality, but in absolute terms, even higher than its selling price.
The Qudelix-5K is a complete and highly versatile device: it is USB, DAC, amplifier, Bluetooth receiver and has a microphone for making calls. In addition, it is ultra simple to use and has a high level of APP, which allows you to control every detail of all the functions it has. It has a 10-band PEQ/GEQ equalizer, long battery life, 3.5mm and 2.5mm outputs and plenty of power, plus a host of configuration options. A technological achievement and, most importantly, a great sound. Needless to say, nothing more is needed.
Earphones and Sources Used During Analysis
- HiBy R3 Pro
- Xiaomi Redmi Note 8 Pro
- Tempotec Variations V1-A
- Smabat ST-10
- Ikko OH10
- NF AUDIO NM2
- BGVP ArtMagic VG4
- ISN H40
- NS Audio NS5 MKII Extra Bass
- Moondrop SSR
- TFZ Live 1
- Takstar Pro 80