Mobile App and Customization

Most users will likely purchase the Qudelix-5K to use as a Bluetooth receiver, which it does very well courtesy the flagship class Qualcomm QCC512x low-power Bluetooth SoC. It is a member of Qualcomm's QCC5100 family, which in itself is an improvement over the CSR8675 used in the FiiO BTR5. There is Bluetooth 5.2 qualification in addition to the usual assortment of ANC, aptX, aptX HD, and aptX Low Latency codec supports, but what is offered ultimately depends on the Qualcomm customer and the device itself. We saw before how Qudelix worked with Sony directly to have LDAC support on the QCC512x SoC, which we have as an option when pairing the Qudelix-5K to an Android phone as above. Qudelix claims ultra-low power consumption in addition to a strong DSP for LDAC playback.


I am going to spoil this page somewhat and say right now that this is the best app for a portable DAC/amp I have ever used. In fact, it is so good that it has near-perfect reviews on both Android and iOS, which hardly ever happens. Anyone using the Qudelix-5K owes it to themselves to install and use the app, which is absolutely necessary to make the most of the device. With the 5K paired to the mobile device already, the app will ask to connect to it, and automatically checks for a firmware update, which was the case here. You are then prompted to update the firmware, which takes a few minutes and is accompanied by a far more granular update progress screen than even I deem necessary. With the Qudelix-5K now updated to v1.9.4, I was ready to proceed.


There is a lot to see here, so bear with me as I aim to give a succinct summary. The app has five menus at the bottom, and each menu has grouped options split into tabs at the top itself. The first menu is named "Device," and aptly so is the first tab here. It is at this point that the product warranty starts, which is an intriguing manner to associate product warranty with the app installation and connection itself. Qudelix has a 1-year warranty on the 5K, which can be increased and transferred to others easily as described here. You are shown the basic status of the device as well as options to turn off, pair, and reset it. There is also support to be had, including a very detailed user manual. Then there's the battery tab which is somehow even more detailed, including real-time battery specifications in charge or discharge and a handy graph. The Power tab sensibly comes next to control how you want to charge the device, over USB connection or in car mode. Next are miscellaneous options, including button configuration and LED brightness, or to have multi-point Bluetooth pairing, which comes set to off by default. Bluetooth pairing allows for up to two devices to be simultaneously connected to the Qudelix-5K, allowing for listening from a laptop and immediately going to a phone call from your smartphone, for example. The About page is the least useful, but I am still glad it is there for a very good reason we will get to soon. Note that the current app version is 1.15.6.


The second menu is Input, and having the Bluetooth icon associated with it already tells you a lot. The active state of data transmission to the Qudelix-5K is displayed here, which is blank when no signal is being sent. The codec tab is extremely useful since it allows you to force the source to use the codec you want, in addition to displaying the latency and LDAC sample rate to show off Qudelix's LDAC strength. These options will impact battery life, and a primer on the page states as much. USB connectivity also gets similar sampling-rate options, as well as a console-specific set of options for when you want to use this with a Sony PS5 or Nintendo Switch. The microphone tab is how I first found out about the built-in mic with the Qudelix-5K, and you can change the mic gain here, in addition to selecting between this and a possible in-line mic if you have it. Given there can be up to two Bluetooth pairings in addition to the wired connectivity simultaneously, the final page allows you to choose which source gets priority should all three want to work with the Qudelix-5K.


The Volume menu changes depend on the output used, which in turn reflects the capabilities of the 2.5 mm balanced output compared to the 3.5 mm one. It also acts as a good home page of sorts, showing the battery level and for control over the two-way volume controls. The first pertains to the source device, which in my case was my Android phone, and the other is the volume control for the device, so what you do thus is to max out the phone volume (at least in the absence of absolute volume control on Android) for best DAC signal output and then use the finer controls on the device or in the app for the volume you want. The DAC/amp menu has different profiles which again prioritize performance vs. battery life, and you can specify the output for the two ports, as well as the specific one for the QX-Over which uses both. There are also plenty of DAC filter choices; pick depending on how you prefer the roll-off, and the accompanying graphs help visualize it. Additional, more detailed information available on this page. The specialized QX-Over gets a tab to itself, including gain settings and actual EQ presets to choose from right then and there.


The final menu is DSP (Digital Signal Processing), and where the equalizer lies. There is a small UI issue here, where the EQ tab seemingly does nothing, but go to the DSP tab and you will see the option to actually turn EQ on/off. Turn it on and you can head back and choose from a wide range of preset EQ options, as well as customize them on a 10-band EQ setting. There is an associated graph, but you need to input the raw numbers, making this more deliberate and less for beginners. The presets come in handy here, as they allow anyone to quickly try out different EQ profiles based on their music genre preference.


Oh wait, did you say the EQ was not based on a table as I described? That was a white lie. You see, I had finished all testing of the Qudelix-5K and QX-Over and was ready to write my review only for the company to alert me to a beta app release that had a few major updates. Available as an apk for Android devices at the time of testing, the new features are already in the latest public release by the time you are reading this. The particular version is 1.16.0, and you now know why I drew attention to the app version before. This brings a new firmware update with it too, and you then see the various changes, including auto EQ presets for hundreds of devices based on the jaakkopasanen/AutoEq database, meaning you will see established EQ profiles generated from frequency response measurements by some reviewers and testers alike to match their specific target curves. This is also why you get the parametric EQ correction in addition to the EQ frequency graph for easier entries, and then there is a whole new EQ preset for the QX-Over earphones from Oratory1990, who maintains an ever-growing list of EQ profiles himself. So I had to re-test the QX-Over with the new preset at Qudelix's request, which I agreed to given the new app and feature set were so extensive they made this already great app more incredible.


For those wondering, this is how the "State" page looks when there is something transmitted to the Qudelix-5K. In this case, I had it in USB mode connected to my laptop with Amazon Music HD playing an Ultra HD song.