Qudelix 5K Reference DAC AMP

After reading a few impressions, and using Fiio BTR5 for more than half a year (and being so unhappy with it that I relegated it to car use, in the meantime going through some other DACs) - I decided to order the Qudelix 5k and try it - particularly after reading that it was a Sony partner when implementing LDAC (this was interesting to me considering the HORRIBLE LDAC/BT performance on the BTR5)



In order to keep this this review concise, I'm going to simply expand each Pro and Con and elaborate:

PROS:

1) Best-in-class, refined sound quality and tuning

When doing a review, it's obviously crucial to have a reference or competitor to compare. In this case, it's none other than the BTR5. I got the Fiio more than half a year ago, and although I was excited initially due to the reviews and design - I grew to almost hate it really quickly - and i've been through 2 of them already. The BIGGEST issue I had with the BTR5 was the LDAC stability. When moving more than 4-5 meters from the source, and/or when going to the gym/biking/for a jog, and keeping my smartphone in one pocket and the BTR5 in another, it would simply be unusable - constant, constant cutouts. I've tried numerous suggestions and "fixes" online, I even exchanged it thinking it was a lemon - no luck, when it comes to BT stability in many conditions, the BTR5's BT implementation is in itself a LEMON. Another 2 things I never liked about it were the sound quality and heft.
The sound always felt blunt, with minimal tuning. It doesn't have the "refined" sound one would expect from a decent DAC, even tough it was rather neutral.
The design was also quite bad - in order to clip it on a shirt, you had to use the case, which was horrible since it already made a very heavy device for it's category even heavier and bulkier. And the disappointment was aggravated by the fact that the in-built mic sounded pretty bad, much worse than an in-line mic on a cable.

Enter QUDELIX 5K. I'm happy to report that in the past week since I got it, I've had 0 (ZERO) dropouts, even when using it on the bike or at the gym - either in a separate pocket than the smartphone or on the t-shirt collar. Besides that - the sound REALLY impressed me. Just to note - I have NOT played around or modified any settings, eq, etc - I just left it standard (DAC- Performance mode - not 100% clear what that means but it's the best setting).
To compare to the BTR5 - it sound MUCH more refined, wider soundstage, better extension. I was so unhappy initially with the BTR5 that I reverted to using the jack on my phone (Sony Xperia 1 mark2 - it has dual Cirrus Logic DACs + DSEE Ultimate sound upscaling AI tech) - though the phone had less power (which didn't matter for me since I've used 2 very sensitive IEMs - Campfire Audio Polaris 2 and Dorado 2020), the sound from the phone had more heft in the lower registries and better separation (which amazed me). I ended up getting a Dragonfly Cobalt for PC use, which was closer (but a bit better) than the phone output.
As far as the QUDELIX 5k - I can say without a doubt that it sound MUCH better than the BTR5 - not a BIT but MUCH. Also, compared to my Xperia 1 II output, it also sounds wider with more headroom, and it's VERY VERY close to the Dragonfly Cobalt, which costs 2.5 times more (the Cobalt has slightly better top-end extension and separation, you have to REALLY listen to it to realise). Suffice to say, I've already sold the COBALT since I have no use for it anymore.

This is valid for both LDAC sound quality, and USB-DAC sound quality, vs the BTR5. I know some people pointed out in some reviews that on the spec sheet, the BTR5 has some dedicated USB controller. How does that help? I don't know, there's no point for a "spec" since it doesn't translate in actual performance. Same story with measurements. I turst what I hear - the BTR5 with it's advanced USB Controller does NOT sound (at all) as good and refined as the Qudelix 5K when used as a USB DAC.



2) Excellent LDAC stability, even at max bitrate (990 kb/s)

Not much to expand more here - as stated at 1), it is absolutely excellent when paired with my Sony Xperia 1 II

3) Lightweight + compact size, in-built metal clasp

This is a HUGE plus, especially over the BTR5. I can now easily clamp it to my t-shirt collar when doing sports activities, and this is all I really needed (as stated before, the BTR5 with the clasp-case was huge and very heavy). This way I can use whatever cable I want, even experiment with balanced, since I'm not forced to use a cable with in-built mic mmcx cable to be able to take calls with the BTR5 - and then when I "jailed" the BTR5 in the car stereo, in order to take calls with my phone (since Campfire Audio headphones, besides the Comet, don't come with a mic), I had to buy a new cable with in-built mic.



4) Very solid app with "transparency" mode and parametric EQ

There is not comparison with the "basic" Fiio app here. The app si excellent and lets you adjust a lot of things. 2 very crucial features, which you cannot find on many (or any?) other such companion apps for BT DACs are the Parametric EQ (I don't need it at all, but some might, it can even transform certain headphones that have issues), and the Transparency mode, AKA "Mic Pass-Thru" (which is amazing). Basically this is like any transparency mode that you can find on most NC headphones (like Sony, Bose or Apple). It lets you adjust how much sound to let through, and is VERY useful when going for a run, on the bike, or even in airports when listening for announcements (this is complemented by the fact that it's light-weight with in-built clasp and can easily be clamped to the t-shirt collar or such, even when doing sports). One small criticism here is that it doesn't seem to work if there's no music playing through the headphones - this is a small minus, and Qudelix should add the feature to always keep the transparency enabled, even if no music is playing - it can be very helpful.



5) Heaps of power for it's class, price and size

Not much to comment here - just check the specs. It has huge gusts of power (more than the BTR5). If you have smth hard to drive, this is your device. Not me though, my IEMs are quite sensitive and low-ohm.

6) Excellent Built Quality

Same here, not much to comment - even though it's plastic + metal clasp, the built quality is very SOLID. The BTR5 is also very well built.



7) Great mic quality

This is a huge + compared to the BTR5. The voice simply comes across as much cleaner and clearer, and you can even adjust it in the app. I can finally buy better cables (balanced also) and experiment without losing the call functionality like I did with the Fiio due to it's bad BT connection and mediocre MIC quality.



8) Great battery life

Simple - I get 1.5-2h more than the BTR5 on Performance + LDAC. that's around 7 hours vs 5.5 (BTR5). This is a straight forward PLUS.

CONS:

1) Buttons a bit flimsy/easy to press + weird location

It is what it is - even though the design is "cute" and the opposite red and blue led for each button looks nice (like a mini Blade Runner hover-police car), they are basically rocker buttons, and they don't have a lot of resistance when pressing - accidental presses are quite easy unfortunately. The location is also not great (on the top corners of the device...why??)

2) No display or button indicators

I personally don't care much for a display since I don't really need to look at it (and eats a bit of battery), but this is simply a feature that is absent on the Qudelix, but is present on the BTR5. Also, it has no button indicators at all.

3) Not water-proof in any way

This is not really a FAIR minus (no other device has IPX rating either, in this category, at least as far as I know) - but considering one of my use cases is doing sports with the Qudelix attached to the t-shirt collar, it gets touched by sweat from time to time, and sweat-proof rating would be a huge addition for reliability and longevity.

4) Although the packaging is nice and unique, a more premium unbox experience would go a long way for brand-awareness

I mean...look at it ) Check more online photos. Yes, there is some innovation there as it's sort of a origami-type technique to make the box so small, it doesn't really scream "cheap" - but having a much nicer box with some extras inside is what many people enjoy when getting a new device and unboxing it, it makes the experience memorable, and it's a very useful marketing tool for companies that want to build customer retention.
It can be argued that this is cost-cutting decision, and it can be justified, considering the device cost is in-line with the Chinese counterparts, but this is built in Korea (higher production costs). But considering the advantages, I think asking for 10% usd extra and shipping it with a premium box would go a long way and would help Qudelix more in the long-run.

5) OTA software update has some issues

This is something that needs to be fixed URGENTLY by Qudelix. Basically, in order to not have a FAILED update, you need to keep the screen open and the app in the foreground during the entire process. Switching out of the app or letting the phone go into idle mode (screen off) instantly freezes the update process, and you need to either repair or reinstall the app. Frustrating. On the other hand, it's not a minus vs it's direct competitior, the BTR5 - that one has no OTA update (as of yet) and needs to be updated in a very "oldschool" manner using a PC, and that also means you need to check the support page on the FIIO website from time to time to even KNOW if there's a new update. The Qudelix app instantly notifies you when there's an update.

6) No way to configure buttons and no way to access smartphone Assistant (Google Assistant/Siri/etc)

I consider this a big functionality omission by Qudelix. Almost every other product in this category (BTR5 included) has a way to map a button to be used as the Assistant activation in order to easily call someone when doing other activities (for example). NO such option on the Qudelix, you can't even re-map the buttons. I really hope this can be added in a future SW update - QUDELIX - PLEASE ADD ASSISTANT BUTTON MAPPING OPTION! 10X!

And that pretty much wraps my review. For reference, this is the gear I've used in this comparison/review process:

Sources: Laptop (USB) and Sony Xperia 1 mark2 (LDAC BT)
DACs: Qudelix 5K (duh!), Fiio BTR5, Audioquest Dragonfly Cobalt (sold)
Headphones: Campfire Audio Dorado 2020 (main), Campfire Audio Polaris 2 (for sale), Sony XBA-N1AP (sold)

Introduction
Qudelix is a new American company, set up by the former lead engineer of the now famous Earstudio ES100. The Qudelix 5K is a new Bluetooth DAC amp, featuring the new CSR8675 BT receiver, one of its main advantages over its competitors, such as the Fiio BTR5 and Shanling UP4. Otherwise, the three feature the same dual ES9218P DACs, balanced and unbalanced ports and a USB-C port, as well as app support. All this can be had for $109.

Package
The Q5k comes in a very simple cardboard box, which includes the BT device, USB-C to USB-C and a USB-C to USB-C cable, as well as some paperwork. The unboxiing experience is simple, but gets the job done 6/10.

Built
The Q5k is made of mainly dark, hard plastic, with only the clip and skrews being made of metal. It feels very solid, but at the same time quite light, lighter than it looks. The whole device is tiny, smaller than the relatively big UP4 and still smaller (by volume) than the BTR5. Considering they have nearly the same specs, this is really quite impressive.

The one downside to the build is that it is made of plastic, as a result it simply doesn't feel as premium as the glass and metal sandwiches of the BTR5 and UP4. I personally wouldn't mind a slightly higher weight, in return for a more premium feeling build, but I do understand the decision. Also, the one aspect that is made of metal, the clip, is non-removable. To me, it feels very solid, like the rest of the build, with good strength, but it could become a problem to replace if broken. Overall, although maybe the not most premium feeling device, it is solid and I have little worries in its long-term durability, therefore it gets a 8/10.

Controls
The device features 4 buttons in total, two on each side. The ones on the right feature a blue light underneath, while the ones on the left have a red light. The light intensity, or when or even if the lights turn on, can be customised to your preference in the app, and so can the functions of the buttons. You can choose which buttons turn on/off the device, skip and go back on tracks and turn up/down the volume, essentially everything you would want. As a result, the controls are very comprehensive and warrant a 8/10 rating, the only real downside again being the plastic build, which include the buttons, as a result the controls are not as tactile as the ones on the BTR5.


Bluetooth Connection
Not much to say here. The device features Bluetooth 5.0 with the newest Bluetooth processor, which supports practically all Bluetooth codecs available. The connection occurs automatically once turned on, and is rock solid once connected, with no hiccups. I've had absolutely to issues with its Bluetooth connection 10/10

Sound
As a declaimer, I'am not very experienced in the world of external DACs, therefore my view might be a bit limited. Also, the following sound impressions have been made exclusively using LDAC and a USB connection only.

The Q5k features a 3.5mm unbalanced and a 2.5mm balanced port. They feature a 2.0 Vrms and 4.0 Vrms power output respectively, meaning it is powerful enough to drive just about any IEM on the balanced port, the same as the BTR5 and UP4.

The sound coming out of the device is of very good quality, especially for a Bluetooth device. It is quite neutral, from bass to treble, with just a slight lift on both ends. It's neither warm nor cold and note thickness is neutral as well. There are multiple minor improvements in sound quality, overall improving the SQ a great deal from a simple smartphone.

To start of with, the bass gets a very slight lift, but the main improvement is in speed and impact, which improve quite significantly. The mids remain quite uncolored and experience probably the least change from the overall sound signature. The treble also features a slight lift in quantity, improving resolving power and adding a but more spice to the sound of your IEM, although not by much. Lastly, soundstage improves quite substantially in all dimensions. Width and depth improve and so does imaging and layering, leading to a more detailed and more engaging soundscape. All these little changes lead to a greatly improved sound, compared to a smartphone. There is further improvement to the sound in all aspects, athough very minor, when connected through the USB port. Overall, this is as good as a Bluetooth receiver will sound at this price 10/10. I've also experienced to hiss through the device, although I haven't used it with a pair of particularly sensitive IEMs.

App
This is really the main advantage of the Qudelix compared to its competitors. The app is quite simply fantastic. It has all of the features a user would ever want, including an excellent parametric equalizer. The app is very well done, with a great user interface, and includes things like a battery graph, volume controls, Bluetooth codec selection DAC/AMP mode, DAC filters, output power and even days under warranty remaing. It is miles ahead of what Fiio or Shanling offer and still gets regular updates.

I have to specially mention the PEQ. It is really good quite simply. Its a 10 band one, which can be either parametric or geometric. It changes the sound very effectively, with little effect on overall sound quality. There are now custom presets that can be used by the user, on top of some pre-made ones. All in all, this might be the biggest reason to get the Qudelix over the Fiio or Shanling. The app gets a straight 10/10 for this.
Battery
The battery life is actually surprisingly good for such a small device, claiming actually to be better than both the UP4 and BTR5. It has a claimed 6-20 hour battery life (depending on volume and power mode. It usually lasts me about 2 weeks of usage with about 1-2 hours of listening per day. It is charged through the USB-C port, and can be used while charging, which is a really nice feature to have. The app also features a battery graph, which is a nice touch.
Conclusion
To sum up, the Qudelix 5k is a fantastic device. There's very little wrong with it. It has a fabulous app, great sound, good built and very good battery life. Compared to the Shanling UP4 and Fiio BTR5, it's smaller, with better Bluetooth connection. To me, this is a absolute no-brainer, if you are in the market for a BT DAC amp. The only real downside for me is just how similar all these BT devices are, but I believe the app on the Qudelix really makes it worth the extra 10-20$ over the latter two. This is as good of a small BT portable amp you can get.

Thank you for reading all the way down here : ) This my one of my first review ever and would highly value any feedback given and I hope that you have enjoyed this review. Also, if any company also enjoyed this review, and would wish to send me some gear to review, I would be delighted to do so.

Specifications





Price: U$D 109.

Shipping costs will vary depending on the country. It is also available from Amazon US.

Many thanks to Qudelix for the 5K review unit.


Design

The 5K has a compact design with a very rectangular shape. It is made entirely of plastic, main body and buttons, with the exception of the attached fixed clip which is made of metal. The plastic material can make it look plain but it is well built and seems solid enough. While an aluminum body could be tougher and more durable, for the better wireless signal the option is either plastic or glass. Glass may be nicer but more fragile and easier to catch fingertips. The clip is strong enough, though I’d preferred it was removable. There is no official case for the 5K but Dignis had already made one.


The layout is pretty simple, well distributed but not the most comfortable. There is a rocker button on each side of the device. Their defaults functions are described on the box, but can be changed from the app settings. I found them logical enough so didn’t mind anyway.


The right side buttons work for power on/off, playback, Bluetooth pairing and managing calls. The left button is for volume control. Below are the functions of each one by default.


Having separated controls for volume and playback is very comfortable. You can press and hold the volume and smoothly adjust it thanks to the up to 120 volume steps and slight increase of 0.5db each. The Fiio BTR3K and BTR5 are more annoying as the same rocker button works for volume and skipping tracks, where you need to make multiple single clicks to change the volume and hold to skip tracks.

There are LED lights under each button that (by default) turn on whenever the buttons are pressed or when pairing the device; blue to the right and red to the left.



The buttons are too sensitive and they are placed exactly opposite to each other, so when pressing one side the other’s side button can be easily pressed. It is not very annoying but needs some time to get used to.

At the upper side are the two audio outputs, single 3.5mm and balanced 2.5mm. To the opposite side there is the USB Type-C socket for charging or for wired DAC use.


There is an issue to note regarding the audio outputs. When using the 2.5mm and then switching to another headphone on the 3.5mm port, the sound will be unbalanced and distorted. The only way to fix it that I found is to turn off the 5K and reconnect it again. This may not happen all of the time but most of it. I’m not sure if it is a particular problem on the unit I received or not, though it seems to be because the device tries to continue to output as in balanced sound mode and does not change back to single-ended.


Software

Like other portable Bluetooth amp/dac devices, Qudelix also offer an application for Android and iOS devices. I don’t own any modern iOS, but with Android it is limited to be used with only 8.0 and higher versions. Well, it was released in 2020 and it is supposed to be used mainly with smartphones so they expect that everyone should own an updated one. Moreover, if you want the best wireless audio quality you’d want a phone that supports LDAC or at least AptX/HD.

The app shows all the technical info about the 5K device, battery time and performance, firmware details and even remaining warranty period. There are various screens that can be accessed by the corresponding icons at the bottom bar, each for a different hardware or software configuration. There is a short description of the many features on each screen. Both the source device and 5K volume can be controlled by the app, as well as changing the buttons’ functions, volume limit, codec, output power and sound quality performance.

A more interesting and probably the most useful feature should be the equalization section. Good news is that all the EQ options can work over BT, including LDAC, and also when used as wired USB DAC. All the configuration and EQ are saved into the flash memory of the 5K so will remain the same when connected to other devices. The EQ is offered in two flavors: Graphic (GEQ) and Parametric (PEQ). On the Graphic EQ are some included presets and 20 extra Custom slots that can be user defined. The Parametric EQ is always much more complex and requires some knowledge and time to use but allows a more precise customization of the sound.

The app performance may depend on the device, and from a Samsung Galaxy Tab with updated Android 8, the app is very stable. Also Qudelix keep releasing updates with high frequency (compared to other companies), and the app is already fairly usable since the recent release of the 5K.


Bluetooth quality

The main purpose for the 5K is to be used as a wireless audio receiver, and Qudelix suggest it is better used with smartphones (Android 8+ or iOS) than with other Bluetooth supporting devices (PC, non-Android audio players, etc.). In fact, the wireless connectivity turns out to be better when used from Android 8+ devices and even more when the app is working. With the Galaxy Tab connectivity is very stable and the wireless range is very good even with a couple of walls in the way, even with LDAC codec on.

Battery

The battery performance is very good on the 5K. It is advertised as able to play up to 20 hours, but of course it will depend on the BT codec, volume level, audio output and audio performance set on the app. Using IEMs and earbuds it easily plays to more than 10h in higher performance and 2.5mm balanced, so the numbers seem rather accurate, and anyway is the best battery time among other BT receivers.


Sound Impressions

The Qudelix 5K follows similar sound characteristics to most of the compact portable sources I’ve tried at this price range. Regardless of their purpose or inner hardware components, from audio players, wired or wireless USB amp/DAC, they tend to present a more or less neutral and uncolored sound. There are always differences in their final tuning when compared to each other, but none of them put much coloration to the sound or go overboard sounding too warm or too bright.

Sound quality on the 5K is very positive. Without using any EQ it is clear, very neutral and clean, presenting no hiss with the more picky sensitive IEMs I could try. The very wide volume range of 120 steps allows a perfectly accurate and comfortable listening with very low impedance IEMs, usually multi-BA or hybrids, and can also get loud enough with more demanding sets without showing major signs of distortion. It can drive IEMs like the final E5000, B1 and Dita Twins with more than decent power, and also 120ohm earbuds, on-ear headphones like SM P55 Vento, and if you insist, the new iBasso SR2 will sound decent enough for such a small device; not my choice, though.

Despite the very neutral signal, there is a very slight sense of warmth to sound that gives a more natural texture. While the low-end is nothing elevated, when using the DK-3001 Pro and Dita Fidelity which are very neutral their bass they gain more body and little more solid impact and decay, and even the 3-BA Fibae 3 sounds less bass light. The midrange is very clear, not particularly airy or open, but less congested or artificial than with the BTR3K/M5 or Shanling M0. The treble quality is particularly good on the 5K. Detailed, clean and fairly natural and a bit smooth, and very good for a BT device. A bit surprising from what I’d expected from a Sabre DAC at this price and compared to the other Sabre based sources where the treble has more brightness and is less forgiving. There are still the usual limitations in terms of average soundstage and extension, but it is acceptable for the price and especially being wireless quality, and the more natural timbre and tonality the 5K presents as a sub $200 source makes up for its limitations.

While the single output works with only one DAC chip, switching to the balanced output takes advantage of the dual Sabre DAC. When changing to the balanced option there is a jump in output power that is clearly audible in the louder volume of around 8dB which translates into ~15 steps in the 5K device volume scale. The overall sound presentation remains unchanged but it is a bit better, more open, with more air and sense of space, especially noticed in the treble response. Not a must but worth using if you already have the setup for it and don’t mind the faster battery drain.