DISLCAIMER
I would like to thank KZ for providing this unit. The AS24 can be gotten here:
https://www.amazon.com/dp/B0C88VYDB7
SPECIFICATIONS
- Driver configuration: 12 balanced armature drivers - 4 x dual 31736 BAs, 2 x 29689 BAs, 1 x 30019 BA, 1 x 22955 BA
- Impedance: 20 - 50 Ohms (tunable version); 20 Ohms (non-tunable version)
- Frequency response: 20 Hz - 40 kHz
- Sensitivity: 109 (tunable version); 112 (non-tunable version)
- Cable: 2-pin 3.5 mm, 0.75 mm silver-plated OFC cable
- Tested at $124 USD (tunable version); $114 USD (non-tunable version)
Do note that there is a tunable and non-tunable variant available. The one that we are reviewing today is the tunable version.
ACCESSORIES
Other than the IEM, these are included:
- 3 pairs of KZ starline silicone eartips (S/M/L)
- 1 pair of foam tips
- Cable
- Tuning switch card pin
For something retailing at > $100 USD, the accessories are a mega disappointment; gear at this price range usually comes with a wider array of eartips, in addition to a case at least. There are even competitors that grace the packaging with modular cables or cleaning brushes once we hit the $100 mark. All these are absent in the AS24's packaging, and that is really not acceptable for the retail price.
The foam tips are suerpb for isolation and taming the treble, whereas the regular KZ starline silicone tips will boost the higher end and provide more clarity/soundstage.
Unfortunately, in addition to a lack of quantity of accessories, there is a sub-par quality too. The provided OFC silver-plated cable is thin and tangly, with microphonics. It does not even have a chin cinch! This is once again a far cry from the usual $100 fare, where we frequently see modular cables of much better haptic quality. During ordering, one can opt for a mic or non-mic version for this cable.
Lastly, we have the card pin to flick the switches, which we will talk about in detail in the following sections.
The rest of this review was done with the stock cable and stock starline silicone tips. No aftermarket accessories were used, so as not to add any confounders to the sound.
BUILD/COMFORT
The shells are made of dermatologically friendly resin, with some pseudo-diamond like faceplate. DLP 3D printed technology was utilized in the fashioning of the AS24's shells, to assist in providing strength and ironing out QC issues.
The earpieces themselves are pretty light. However, they are very large, which isn't unexpected considering the need to squeeze 12 balanced armature drivers inside. KZ advertises that they designed the housings after incorporating data of a myriad ear anatomies, but I found that the ergonomics was pretty hit or miss due to the huge shells. They protrude out of the ears quite a lot, and may be fatiguing for longer listening sessions.
Being an all -BA set, we won't talk about driver flex. Interestingly, the BA bass seems to be vented, which isn't common for an all-BA IEM. However, as a result of the venting, isolation is about above average, but not as solid as other unvented BA types.
DRIVABILITY
I tested the AS24 with the following sources:
- Apple dongle
- Cayin RU7
- Colorfly CDA M1 DAC/AMP dongle
- Creative Sound Blaster X5
- E1DA DAC/AMP dongle
- Hiby R3 Pro Saber 2022 DAP
- Khadas Tone Board -> Schiit Asgard 3 amp
- Khadas Tone Board -> Topping L30 amp
- Questyle M15 DAC/AMP dongle
- Sony Walkman NW A-55 DAP (Walkman One WM1Z Plus v2 Mod)
- Sony Walkman NW A-55 DAP (Walkman One Neutral Mod)
- Sony Walkman NW WM1A DAP (Walkman One WM1Z Plus v2 Mod)
- Smartphone
This IEM is relatively easily driven, but the impedance of the IEM does depend on what switch settings are flicked into play. Generally though, amplification is not required for the AS24.
INTERNALS/TUNING SWITCHES
This 12 BA behemoth houses the following drivers:
- 4 x dual 31736 array-design BAs handle the lower and upper treble frequencies
- 1 x 30019 BA is responsible for the upper midrange/lower treble
- 2 x customized 29689 BAs settle the midrange
- 1 x 22955 BA (vented) takes care of the bass.
On the bottom and back of each shell, we each have 1 tuning switch board (a main and an auxiliary one), with 4 tuning configurations for each board. The switches are extremely tiny, and those with poor eyesight or dexterity issues may have difficulty manipulating the switches. The switches seem to be of good QC and flick easily - I encountered other tuning switch IEMs that had stuck switches in the past, so thankfully the ones of the AS24 seem properly implemented.
These are what the switches do, according to KZ's marketing materials:
Potentially, we will have a mind-boggling 256 tuning permutations with the AS24!
From independent graphing of the most extreme of tuning switches, these are the potential graphs of what the KZ AS24 can sound like. This monster can sound like a bassy V-shaped set, to something more neutralish/U-shaped, to something neutral bright. The rest of the other 256 options fall somewhere in between these tunings. The versatility is really excellent, and is one of the feathers on the cap of this IEM. Indeed, I don't think there is an IEM out there that can boast of 256 tuning options haha.
Graphs of the KZ AS24 with the most extreme of tuning switches. 8 kHz is a coupler artefact peak.
SOUND & TECHNICALITIES
For the rest of this review, we will be utilizing the all switches up config, which confers a V-shaped tuning.
On this setting, the AS24 is a sub-
bass focused set, with quantity just north of neutral. While not exactly sounding identical to DD bass, the AS24's vented design does allow the bass to sound more natural than other all-BA sets in terms of bass decay and movement of air. We have decent sub-bass extension and some rumble. Bass texturing is average - and may sound one-noted at times - though the speed is fast, with minimal mid-bass bleed.
The lower
midrange is recessed on this configuration, but without big bass to encroach here, it is quite transparent and clear, allowing instruments to be easily pinpointed. The upper mids are forwards without overt shoutiness, unless used at very loud volumes (Fletcher Munson curve).
With this setup, the
treble is quite bright, with moderate air and sparkle. There is marked sibilance and some harshness noted in the lower treble region, with overemphasized high hats and cymbals. Treble-sensitive folk might want to experiment with foam tips, or perhaps check out the least bright switch settings.
The AS24 sounds very metallic in terms of
timbral accuracy, and this is arguably one of the major weaknesses of this IEM. Vocals sound nasal, and acoustic instruments like strings, woodwinds and brasses sound artificial. This IEM may not be the best option for timbre freaks or for genres like jazz, vocals or classical as such.
Where the KZ AS24 aces (and redeems itself), is in the
technicalities department. Resolution, clarity and micro-detailing are very good for a low $100ish set, with solid instrument separation and imaging. Soundstage is about average in width, but has good depth and height.
COMPARISONS
Some $100ish USD tunable gear will be taken out for comparisons against the AS24.
Hidizs MS3
The MS3 has 3 tuning options via nozzles, from a warmish bassy tone to a neutral bright signature. On the gold (balanced) nozzle, which is the mid-point tuning of the 3 options, the MS3 is brighter than the AS24, with greater air and sparkle, though it is probably more fatiguing than the AS24.
The MS3 has similar instrument separation, but has better micro-detailing, soundstage width and imaging. The AS24 is better in soundstage depth.
Kiwi Ears Quartet
The Kiwi Ears Quartet has 4 tuning options via switches. Across all tuning switches, the Quartet is darker in the treble, with a thicker note weight and a more natural timbre.
Unfortunately, the Quartet is leagues behind the AS24 in technical chops, with inferior soundstage, micro-detailing, imaging and instrument separation.
TRI Starsea
The Starsea has 4 tuning options via switches, but they are all quite similar tonally. So from a versatility point of view, the AS24 is superior.
The Starsea has slightly better imaging, but otherwise loses to the AS24 in other technical areas such as soundstage, instrument separation and micro-detailing.
The Starsea has a bad pressure suction effect on the ears, plus driver flex, which may be deal breakers for some users.
CONCLUSIONS
KZ and TRN are famous (or perhaps infamous?) for their multi-driver nuclear race, and KZ has upped the ante with 8 tuning switches to provide a possible 256 tuning permutations in the AS24!!! KZ is quite extravagant to say the least! Unlike other "tunable" rivals which have minimal or very subtle changes in sonics, the AS24 does have quite marked tonal differences on graphing.
The AS24 also sports good build and easy drivability, and technicalities-wise, it is one of the better sets at the low $100ish range. Despite packing BA drivers for the bass, the bass does not sound as anemic as some BA bass IEMs due to the addition of venting.
Well, considering that one can get multiple pokemon - 256 to be exact - to evolve out of this primary KZ pokemon, the versatility is really overwhelming (and may be an overkill). On the flip side (no pun intended), some lay consumers may be confused as to what the tuning switches do, especially if they do not have graphing rigs.
There are some other areas where the AS24 loses marks in my book. Firstly, the accessories are horrible, and I've seen sets at 1/3 the price which pack way more goodies. Comfort is also hit or miss due to the large shells needing to accommodate 12 drivers per side, and the tuning switches are really miniscule - folks with eyesight or dexterity issues might find it problematic to toggle the switches. One major bugbear of mine is the artificial timbre, and this IEM may be a bit peakish for our treble sensitive brethren on some settings.
Nevertheless, the above average isolation, versatility and technical prowess does make this IEM a suitable option for audio work or stage use, and analytical heads and folks wanting something for critical listening will not be disappointed here. Listeners who prefer something more natural or organic sounding might want to look elsewhere though.
