Fit and Comfort

You get three silicone tips with the QX-Over, and I have to say that fit and comfort could certainly be better. The relatively slim and long profile of the ear buds means there is some play in how they fit in the ear, and I never really felt there was one specific and correct installation either. Seen above is the right ear bud with the size M tips inside an artificial ear mold, which works well in representing my own experiences. Once they feel secure enough, the cables just hang down without a securement point, as with IEMs going around the ear at least, but the ear buds are so lightweight the cables are not under any tension—there is little reason the ear buds will slip off easily. There is also a good deal of passive isolation, and the silicone tips do their best in maintaining it even though memory foam tips will beat it in this regard.

Audio Performance

Audio Hardware

The use of dual 8 mm dynamic drivers is what dictates the shape of the ear buds, but Qudelix is unfortunately short on further details about the driver units. The active digital crossover with the Qudelix-5K is by far the biggest thing of note here, so much so that the lack of more specifications, such as earphone impedance, sensitivity, THD, etc., is irrelevant given you can't really use these with other sources anyway.

Frequency Measurement and Listening

I will mention that I have a general preference for a warm neutral signature emphasizing a slightly elevated bass and smooth treble range with detailed mids and good tonal separation. I also generally prefer instrumental music over vocals, with favored genres including jazz and classical music.


Our reproducible testing methodology for IEMs and earphones begins with a calibrated IEC711 audio coupler/artificial ear that ear buds can feed into enough for decent isolation similar to real ears. The audio coupler feeds into a USB sound card, which in turn goes to a laptop that has ARTA and REW running, and the QX-Over earphones are connected to the laptop through the Qudelix-5K in wired mode. I begin with an impulse measurement to test for signal fidelity, calibrate the sound card and channel output, account for floor noise, and finally test the frequency response of each channel separately. Octave smoothing is at the 1/6th setting, which nets a good balance of detail and noise not being identified as useful data. Also, the default tuning was used for testing, and no app-based settings were chosen unless specifically mentioned. Each sample of interest is tested thrice with separate mounts to account for any fit issues, and an average is taken of the three individual measurements for statistical accuracy. For wired earphones, I am also using the ear mold that fits to the audio coupler for a separate test to compare how the earphones fare when installed in an artificial pinna form factor to better represent our own listening experiences and not just the audio coupler by itself. The raw data is then exported from REW and plotted in OriginPro for easier comparison.


The IEC711 is such that you can't really compare these results with most other test setups, especially those using a head and torso simulator (HATS). The raw dB numbers are also quite contingent on the set volume, gain levels, and sensitivity of the system. What is more useful information is how the left and right channels work across the measured frequency response in the QX-Over earphones, and I went with the standard 20 Hz to 20 kHz range here. The left earbud was separately tested from the right one, and colored differently for contrast. I did my best to ensure an identical fit for both inside the IEC711 orifice, so note how the right channel ends up slightly boosted in the sub-bass, with that small peak in the right channel ending up a measurement artifact, as I was not able to discern it in my own listening. Otherwise, there is little differentiating them, with a <1 dB difference across the board until you get that ~8.5 kHz peak where things split further. This is of course considering that the IEC711 isn't all that reliable at higher frequencies, but any differences between the two channels seen above are once again not felt.

I will also mention that there was no discernible break-in period or effect, so there is overall good reproducibility and consistency since the average response for each channel is basically the same across the three repeated tests. Looking at the effect of the ear and cheek simulator with the artificial pinna included, we have a smoother transition from the lower mids to the mids proper and a better transient response in the highs. That weird 8.5 kHz peak is mostly resolved, and the perceived darkness with the roll-off past this point in the IEC711 also is not there when you listen to them in your ears. This is why that artificial ear test comes in handy even if the silicone is slightly stiffer than the human pinna.


At this point, I was ready to talk about my listening experience with the QX-Over earphones, but then the new app update hit, and Qudelix requested I test these out with the Oratory1990 preset EQ as well. Since it was a specifically named request, I went ahead and actually did the EQ-based measurement here, which I generally do not since everyone has different tastes. Indeed, Qudelix itself still maintains that the company prefers the default tuning with the QX-Over, but acknowledges that many prefer the Harman target curve. Oratory1990 does this for all uploaded measurements and EQ presets, which has been added to the Qudelix app for these, making it extremely simple to do. The graph above with the two frequency responses normalized at 1 kHz shows an absolutely massive difference in the stock response compared to this EQ. I will also note that the EQ preset does it the right way by lowering the regions that need to be recessed rather than boosting the rest, which can introduce noise and affect sound quality.

I have zero issues with anyone doing EQ, and have done it myself at times, but also understand Qudelix stating that they prefer the stock tuning. Yes, this applied EQ profile makes the QX-Over more balanced, but character I was actually enjoying from before is lost. The QX-Over with the dual dynamic drivers was tuned to strength with an unabashed V-shaped signature, having a dominant bass response with very good tonal separation. Bass guitar in funk music in particular sounded great, which the Oratory1990 EQ profile takes away. You still get very good sub-bass with the EQ profile, and that random peak here once again confirms it was clearly a fit issue and measurement artifact on the IEC711 itself.

The mids are really the reason to go with the EQ profile, with the lower mids now having more range coupled with the active digital crossover adding more strength than on the original tuning. Male vocals are excellent, including with metal music. Hearing Lemmy rock out and sing Ace of Spades was how the EQ profile convinced me more than anything else, with his legendary growl coming out of the QX-over very well. Imaging is on point too, with the various instruments in metal, pop, and country music alike easy enough to identify as point sources. Jazz and classical music in general weren't really strong to begin with, and I suppose the EQ preset was more akin to applying a band-aid over a leaking dam. The upper mids are too energetic for my tastes on either profile, which is extrapolated with female vocals. The in-ear resonance compensation is also broader than it needs to be, before the smoother transient response with the EQ profile helps with string instruments and the roll-off comes in, quenching things in the highs altogether. I suppose I need to complement the QX-Over in that the experience in the lows and mids led to a higher standard than the weight-class the QX-Over operates in price-wise, which has the mediocre response elsewhere, including with the narrow soundstage in its stock profile, feel worse by comparison to its own high standards set thus far. The Oratory1990 EQ profile does not really aid in getting a wider, deeper, or taller soundstage, which had it come off as an intimate setting—owing to the good imaging here, inside a small music club listening to a live performance, for example.