Fit and Comfort

I have mixed feelings about fit and comfort, and having just a single type of ear tips in the box is not the crux of the issue, either. The CCA CA24 is relatively substantial in size owing to all the hardware fitted inside, so it won't fit fully inside smaller ears as much as medium to large ears, which are much better at just accepting the ergonomic fit of the shells. Seen above is the pre-installed size M ear tip installed on the right IEM and inserted into an artificial ear mold. I have average-sized ears, and the ear mold above represents my own experiences well enough as a proxy. Size M silicone tips are my go-to for testing since foam tips are not included by some. Assuming you do get the fit right, there's still the annoying cable that may not cooperate with the best-possible seal. See above for an example of what I mean—the IEMs are rotated to match the concha shape well, but the cable now wants to hang over the ear rather than go around the back. In fact, the IEMs may well be more comfortably placed if rotated further counter-clockwise, but that would make things worse with the cable not even going past the ear. The memory-wire formation on the cable makes this worse, as does the fixed angle on the connector housings. Somehow, the cheap cable found more ways to make my user experience worse! Don't forget there is no cable cinch, so the cable effectively just drapes over the front and is more prone to microphonics than usual. Getting a cable clip to secure it to your shift or dress is not a bad idea thus. Once fit in, the IEMs themselves are comfortable owing to their ~7.5 g mass each and the vents making for a good balance of air-pressure balance and passive isolation.

Audio Performance

Audio Hardware

The CCA CA24 is easily the most complex set of IEMs I have reviewed to date, although it would still have played second-fiddle to at least one other set had things gone as planned. But that's a story for another day, and seen above are some images provided by CCA to better illustrate the inner workings of the CA24 with its 12 balanced armature drivers per side. These are fit into a 3D-printed acoustic chamber to allow for precise driver positioning; these handle different segments of the target frequency range, with an electronic crossover between them, too. CCA is making a big deal about using "Black Gold King Kong series" balanced armature drivers, claiming these are better than generic ones. Unfortunately, these are still not as good as the likes of Sonion or Knowles BA drivers, which also cost significantly more, and we now get to solving the puzzle behind how a budget IEM company goes about marketing a lot of drivers per IEM as a selling point. I won't go into more detail since the images above are self-explanatory, but note the 5-way crossover and understand there are plenty of challenges to engineer around here.

It may thus seem that driving the hardware would be hard, but it ends up not so. The CCA CA24 has a rated impedance of 30 Ω and slightly under average sensitivity of 103 dB/mW, making it one of the more demanding IEMs, but nothing any practical source you already have in mind wouldn't be able to handle. A standalone DAC/amp is not a bad idea if you do not have one already, and going with one of the portable Bluetooth options we have covered before also makes this a wireless solution. The lack of a 3.5 mm audio jack for most phones these days is another reason to consider a DAC/amp that takes digital input and provides a 3.5 mm jack since you will otherwise have to use an adapter anyway, or even a dedicated DAP. If not on the go, space is less of an issue, but the short cable might be a potential handicap if connecting to a PC as the audio source. I was able to get plenty of juice from my laptop's Realtek audio codec-powered 3.5 mm jack even with the volume in Windows set to 50%.

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 begins with a calibrated IEC711 audio coupler/artificial ear IEMs can feed into enough for decent isolation. The audio coupler feeds into a USB sound card, which in turn goes to a laptop that has ARTA and REW running and the earphones connected to the laptop through the sound card. 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 1/12th 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 IEMs, I am also using the appropriate ear mold fitted to the audio coupler for a separate test to compare how the IEMs fare when installed in a pinna geometry and not just the audio coupler. 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 rated frequency response in the CCA CA24, or at least the useful part of it. The left channel 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 two channels are similar enough most of the way to be within tolerance. Indeed, the gap is within 1–2 dB in the lows and mids proper, but deviates past the mids proper, which has channel matching take a hit, especially in the 5–7 kHz range, where it's immediately apparent. Measurements taken after 50 hours of testing, including with these playing a mix of various songs as well as white or pink noise and sine sweeps, showed no difference. There was no perceived burn-in effect thus, and none was measurable, either. The response with the artificial pinna in place matches the ideal scenario in the coupler very well, including with the typically seen resonance shift.


This is the average frequency response for both channels of the CCA CA24 plotted against my personal target taken from VSG.squig.link, which also gives you an idea of my personal preferences to better correlate any possible biases. The tuning of a set of headphones or earphones does not have to match my target as long as it is tuned with some direction, makes sense, and is executed well. After all, no one set will appeal to everyone, and having different options is what makes this hobby so interesting and hard to quantify. That being said, this set is obviously tuned for a V-shaped signature, which gets quite extreme at that!

The CCA CA24 is not a balanced set of IEMs. Heavily bass emphasized because of its 15–16 dB bass elevation relative to the lowest SPL value in the mids, it caters to none of my specific listening tastes. If you happen to listen to the music genres I do, you most likely will not enjoy the CCA CA24, either. But if it is to your liking, who am I to judge? My job is to see if the tuning makes sense and is executed well. I can't say CCA has done either, unfortunately. The best thing about the bass is that there is lots of it for bassheads to relish, including with good extension into the sub-bass courtesy some of the 12 drivers dedicated to handling the low frequencies. It also does not come off as too bloated in the mid-bass, but there isn't much impact behind it. The CCA CA24 is a great example of why some do not think all-BA sets can handle bass well, especially compared to the relatively stellar job the likes of SeeAudio, FiiO, and DUNU have done.

There is bass bleed into the lower mids, too. The recently reviewed FiiO x Crinacle FHE:Eclipse shows how to do bassy IEMs while still being tuned well to where CCA has little excusing it. Male vocals and bass guitars get muddy in a way that reminded me of the Meze 99 Neo and its distortion here, which isn't good. There is also a clear point of crossover that feels more passively than electronically done, so much so that some of these drivers just don't feel as good as others. It could be a case of poor driver quality, but I don't know enough about these to say for sure. It has convinced me that the number of drivers doesn't matter as much, especially if they aren't backed by tonality and technicalities. The haze in the mids and relatively weaker channel separation results in poor imaging, though I was pleasantly surprised by the soundstage.

The upper mids are well executed, and I can see a specific niche of female vocals and pop music fans appreciating the CCA CA24 more than others. The pinna gain is accounted for better than with many other IEMs too, and in the right places, except for perhaps peaking too early, but this will vary from person to person. But all the good done here is immediately let down by the tuning in the high frequencies, where the less is said about the treble performance, the better. Even though I had two different implementations courtesy the channels not matching well, I hated both of them to where this had me frustrated instead of just disappointed as before. Notes get shouty and sibilant, which is made worse by the 5 kHz peak that is so much higher than anything before and after. Note that the IEC711 coupler tends to have a resonant peak around 8 kHz, so the dip is even worse in actuality since some of that is being propped up by measurement artifacts. Instruments have no room to shine outside of some piano fundamental tones, so don't consider the CCA CA24 for anything orchestral.

Comparisons

The CCA CA24 falls into a price range where I don't have many other apt comparisons to make, with the TinHiFi T5 being another extreme tuning that misses out. I've gone slightly higher to show the aforementioned FHE:Eclipse which, at $150, would absolutely be the better of the two in both tonality and technicality. It's a 3-driver setup that proves my earlier point of the number of drivers absolutely not mattering as much as the type and implementation of said drivers. But if you were strapped for cash and still wanted the bass-boosted V-shaped tuning, maybe consider the $50 Tripowin TC-01 instead, which is V-shaped tuning done well, without bloat, bleed, and extended treble from a single dynamic driver. To seal the deal, it also comes with better accessories.