Closer Examination

We know by now that Qudelix prioritizes function, and the design language of the Qudelix-5K says as much with a blocky form factor akin to a 9 V battery. In fact, the Qudelix-5K is only slightly larger than one of those and comes in at 52.8 x 26.7 x 15.6 mm while weighing 25 g. The all-black construction with perpendicular corners is also a change from the rounded corners and glass bodies of the FiiO BTR5 and EarMen Sparrow we saw recently, which makes this less pocket-friendly as a result. Good thing then that there is an integrated clip on the back! The body is also black plastic, with the front mostly bare aside from a subtle Qudelix logo at the bottom. This is what most people will see in use, so I do admire the company for going with minimalist branding and letting the product speak for itself.

On the back, we see contact information for the company and the certification for the Qudelix-5K itself, and that's about it. The I/O is on the two smaller sides, with a cover plate held in place by what appear to be security Torx screws. These are smaller than T6 based on my attempts to disassemble the unit and failing spectacularly. In addition to Bluetooth connectivity, there is a USB Type-C port for wired connectivity and to charge the internal battery. This is where the two provided cables come in handy; them being 12 cm long and flexible also has them perfectly wrap around the Qudelix-5K and to the back of the source—a smartphone, for example. The other side has the two outputs, a 3.5 mm TRS port and a 2.5 mm TRRS balanced port.


It is at this point that we see the gap between the actual body of the Qudelix-5K and integrated metal clip, which acts as the de-facto back of the device. There is a hinge mechanism on the side by the output ports for the user to clip the device on the other side, further away from cables feeding it. This hinge is quite robust, and I appreciate having an integrated clip as opposed to the add-on case/clip FiiO adopted. On either side of the hinge is also where we have the button placement.


While it may not look like it, there are four buttons on the Qudelix-5K, which make it a standalone product. Now, I do think the screen on the BTR5 was excellent in this regard, which you obviously lose out on here, in addition to the NFC tag. In return, you get two sets of two buttons, of which one has a notch to aid in touch identification. One set does volume control and the other turns the device on/off and initiates pairing mode for wireless connectivity. Red and blue LEDs associated with each help further identify which button does what.


Here is a quick visual comparison of the Qudelix-5K alongside other portable DAC/amps I have on hand, including the two we saw before. The FiiO BTR5 is the only other hybrid wired/wireless DAC/amp unit, as the other three are wired only. This explains the increased width of the Qudelix-5K since it has to accommodate the 500 mAh Li-polymer battery inside.

Only three of those above provide dual outputs, all by adopting the 2.5 mm balanced + 3.5 mm single-ended combination owing to size limitations. This is a bit of a shame since it seems the 4.4 mm balanced connector has proven more popular for portable headphones and IEMs alike when it comes to balanced cable options, but I can't fault Qudelix for not doing so with the Qudelix-5K. As with most such devices, the Qudelix-5K has a fully balanced architecture since each channel is driven by its own separate DAC and amplifier. This means you will get more output power from the balanced option, which goes as high as 240 mW at 32 Ω instead of 80 mW with the single DAC solution on the 3.5 mm output. This allows for plenty of juice in either case, but go the balanced route if you need that extra power. Qudelix has some power budget numbers for a few popular headphones on this page for a better idea of how much this small thing can handle.


Given my failed disassembly attempts, I am using Qudelix's own photo of the PCB employed with the 5K. We see three BGA SoCs in the form of the Qualcomm QCC5124 as well as two ESS Sabre ES9128P DACs. The DACs in question are quite similar to the two ES9218P ones used in the FiiO BTR5, down to the power output from each port. Qudelix says there was an added epoxy under-fill step on each BGA component for added stability despite the increased cost, thus making for a second contact bond with the epoxy on top of the soldering itself. There's also a high-sensitivity 3D RF antenna in the case for good RF performance without much interference as long as you avoid direct contact with metals.