KZ AS24 Pro
I was contacted by Kate, the social media representative at KZ, and was sent a review sample of the new AS24 Pro. It features 12BAs per channel and retails for around $115. There are two versions, one with tuning switches and one without. The model reviewed here is the tuning version.
The Packaging
The AS24 Pro comes in the familiar KZ small black box with a white sticker on the side bearing the product information. Sliding the box open reveals the IEMs in a cut out, below which the accessories are stored under a cardboard flap.
The contents comprise:
● AS24 Pro IEMs
● Silver plated 2-pin cable
● Three pairs of “Starline” tips (S, M, L)
● One pair foam tips (M) pre-fitted
● Tuning lever
● Documentation
The packaging is rather basic and although acceptable for KZ’s more affordable models, it is disappointing at this price.
Build and Design
The KZ AS24 Pro has a black resin earpiece which is a similar shape to earlier models such as the AS16 Pro. The faceplate has a geometric design with a gold-coloured 3D pyramid effect and below this, the model name “AS24 Pro” is written in a freestyle font along with channel identification. The BA drivers are visible through the smoked grey body and the four tuning switches can be found on the rear of the capsule. The black nozzles, which are rather short, have a white filter and the clear plastic 2-pin socket is mounted on the top surface. There is a small pinhole vent in the centre of the underside.
Internally the BA driver complement comprises:
1 x 22955 BA for the bass frequencies
2 x 29869 BAs for the midrange
4 x 31736 dual BAs for mid/high area
1 x 30019 BA for the ultra high region
The BAs are connected by 3D printed sound tubes and there are no BAs within the nozzle. There are four tuning switches on the rear panel and they operate as follows:
Switch 1: increases bass by one level
Switch 1 & 2: increases bass by two levels.
Switch 3: reduces ultra-high frequency by one level.
Switch 3 & 4: reduces ultra high frequency by two levels.
All switches off: Basic tuning.
The cable is a silver plated copper type with a 2-pin 0.78mm connector and a gold plated 90° angled 3.5mm plug. The sheath is transparent, revealing the wire within. This is the same cable which is supplied with KZ’s most basic models and it is rather disappointing that it is included here. The cable is not as prone to tangling as previous KZ designs but there is still no chin slider. There was no problem with microphony during use.
Fit and Isolation
The AS24 has rather short nozzles, so after removing the pre-fitted foams and substituting some large wide-bore silicone tips, I obtained a comfortable fit with good isolation, external sounds being considerably muted. The earpieces are somewhat bulky and do protrude from the ears but they have to accommodate 12 BAs!
Sound Impressions
The AS24 Pro was tested with Xduoo X20, Sony NWZ-A15 and Hidizs AP80 Pro X DAPs. A smartphone, via a USB-C dongle, and a digital radio were also used and the IEMs were subjected to a burn-in period of 100 hours. The source used for the review was an Xduoo X20 DAP. Using the stock cable and tips, I found the tonality a little thin and bright, so after trying various cables and tips, I settled on a hybrid copper/silver cable and large wide-bore tips. This produced the desired result. After some experimentation I set the switches to 1100 which gave a better balance and deeper bass.
Tonality
Once the correct tips and cable were fitted, the AS24 Pro impressed with deep solid bass, a highly detailed and open midrange and very clean, extended treble. Technicalities were also excellent with superb separation, layering and imaging. The coherence between the 12 BAs was seamless with the drivers giving the impression of a single unit.
Bass
With the switches set to 1100, the AS24 Pro proved itself capable of a healthy bass response with a deep sub-bass rumble while at the same time displaying excellent speed and control, as would be expected from a BA. Mid bass was fast and punchy displaying good impact with texture and resolution top-class and the reproduction of studio ambience very well handled. Timbre and tonality were very natural.
Andrew Forrest is an electronic music artist based in New Zealand. His music falls into the “Cosmic” or “Berlin School” category, featuring longer tracks with the prominent use of sequencers. “Through the Seventh Stargate”, from his album “Infinite Octaves” is a typical example. Beginning with swirling electronic effects and sparkling percussive touches, a slowly descending theme appears, supported by a deep sub-bass drone. The AS24 Pro reproduced this in great style with good texture and resolution. As the piece comes to a climax, the bass synths reappear, supporting the powerful minor key melody and the AS24 Pro rose to the occasion admirably with a solid and weighty rendition, bringing out the drama of the composition.
Jacques Ibert’s “Escales” (Ports of Call) is a lively and colourful suite of pieces inspired by travel. The third part, “Valencia” evokes a scene imbued with Spanish culture, featuring characteristic rhythms and melodies. The orchestration is rich and full with prominent parts for tuba, timpani and bass drum. All these were brought vividly to life by the AS24 Pro in the wonderful recording by the Minnesota Orchestra under Eiji Oue. The resonance, decay and timbre of the bass drum was a joy to behold and the crisp edges of the tuba very realistic, all within a believable natural acoustic with the bass BA giving a performance worthy of a top quality dynamic driver.
Midrange
The midrange was open, clear and highly detailed with no recession, nor was there any evidence of bass bleed. The tonality was consistent across the range from the mid-bass to the boundary with the treble, stereo imaging and separation were exemplary and the timbre throughout was natural with a slight tilt towards brightness which endowed the sound with a “live” feeling. Vocals, both male and female, were well presented with an “etched” quality which brought them slightly forward in the mix whilst displaying excellent clarity and diction.
Al Stewart’s “Year of the Cat” is perhaps his finest album. The second track, “On the Border” begins with a fast-paced rhythm on piano and percussion backed by strings. A lively bassline is added followed by Al Stewart’s vocals. The AS24 Pro handled this well with the vocal located precisely in the centre of the image with clear diction and in perfect balance with Alan Parsons’s complex and imaginative production. All the detail of the accompaniment was audible and there was an attractive urgency in the presentation. Peter White’s acoustic guitar solo came through very effectively and the character of Stewart’s voice was preserved very well, adding to the enjoyment.
E.J. Moeran’s “Sinfonietta”, written in 1944, is inspired by the landscape of the Welsh Marches. The second movement, Theme and Variations, is replete with rich harmonies and features a lyrical pastoral melody with a Celtic flavour. The tonality of the various instruments was conveyed accurately and satisfyingly by the AS24 Pro with bright, crisp brass, smooth well separated strings and characterful woodwind. There is a section later in the work where a sustained melody is accompanied by a series of chords exploring remote harmonies. This was particularly impressive on the AS24 Pro and the richness and colour of the orchestration was portrayed charmingly with depth and feeling in this classic recording on Lyrita by the New Philharmonia Orchestra conducted by Sir Adrian Boult.
Treble
The treble performance was exceptionally clear and extended. Resolution was also superb with the finest details coming through with an attractive delicacy. The tonality was just a tad on the bright side of neutral but remained smooth and airy without displaying any undue harshness. Sibilance was well controlled, only appearing when present in the recording and there was good speed and transient attack.
Iasos (Joseph Bernadot) was a pioneer of New Age music and described his compositions as “concentrated beauty patterns”. His first album, “Inter-dimensional Music” was released in 1975, at around the same time as Steven Halpern’s “Spectrum Suite”. “Realms of Light” (2001) is typical of his style. “The Fountain of Creation” begins with a rising arpeggio which extends well up into the extreme treble. The AS24 Pro reproduced this thrillingly with a clean and precise delivery. Set against swirling synth chords, a stately melody shifts and changes, backed with rich harmonies. During this section, the high frequencies remained clear and articulate even within the more dense and complex passages
Samuel Barber’s “Adagio for Strings” is a frequently recorded piece and rightly so, but it has perhaps never received such a performance as that by the New York Philharmonic under Leonard Bernstein. The measured pace brings out the feeling of the piece, allowing the emotion to build. At the climax, the high strings reach a cathartic point and the clarity, separation and detail provided by the AS24 Pro really conveyed the message in the music and the contrast in the final bars was beautifully depicted.
Soundstage
Although being a pure BA design, the AS24 Pro’s staging more resembled that of a vented hybrid or dynamic driver IEM with an expansive presentation featuring excellent imaging, layering and separation with a very good representationof height. Movement was particularly well rendered due to the high level of detail on offer. There was plenty of “air” in the upper register and recorded ambience was very authentic due to the good bass extension.
“Dawn”" is the final track on the album “Summer Suite” by Sky Canyon (formerly Rising Sun). Deep synthesised bass tones introduce the piece, accompanied by electronic beeps and percussive elements dancing around the image. Teja Bell’s acoustic guitars and Dallas Smith’s Lyricon appear and the piece becomes more densely orchestrated as bass and more electronic voices are added. The AS24 Pro handled all this with aplomb with each strand easy to follow, maintaining treble clarity while the whole piece gelled together musically.
Gerald Finzi’s “Severn Rhapsody”, written in 1923, is a characteristic pastoral idyll with luminous textures and obvious folksong influences. In the version by the LPO under Sir Adrian Boult, the AS24 Pro presented this beautiful Lyrita recording in all its glory. The positioning of instruments within the orchestra was authentic and accurate with each instrument revealing its own character in its own space. Woodwind was particularly well reproduced with plenty of air and natural timbre. The ambience of the hall came over convincingly with a realistic sense of front to back perspective and a real feeling of atmosphere.
Comparisons
KZ AS16 Pro
The AS16 Pro, with 8 BAs per channel, is a redesign of the original with a new faceplate. It also uses a different array of BAs as below:
4 × 31736 BA (treble)
2 × 29689 BA (midrange)
2 x 22955 BA (bass)
The AS16 Pro has an assertive V-shaped profile with solid bass, forward mids and bright treble. There is a mild “hardness” in the stock configuration. The tuning is more traditional KZ style than the more recent releases. The AS24 Pro has more detail, a more extended treble and a larger stage. The AS16 Pro has a similar level of bass even though it has an extra driver, but the tonality is not as natural as the 24 Pro. The shortcomings can be alleviated by the use of a 30 ohm impedance adaptor and a pure copper cable which add warmth and tame the upper register. However the 24 Pro improves on the 16 Pro in all areas. Price is a consideration, but the 24 Pro is definitely worth the difference.
KZ AST
The AST is KZ’s former flagship 12 BA design. It employs the “black” s-type BAs in the following configuration:
1 x 22955s low-frequency BA
1 x 29689s medium-frequency BA
2 x 30017s medium/high frequency BAs
6 x 50024 high-frequency matrix BA
1 x 30019s high-frequency BA
1 x 30095s high-frequency BA
The AST is tuned to be smooth, warm and well-balanced. The bass is firm and solid and is just a little softer than that of the 24 Pro. Midrange is less forward than the current model and sounds easy-going and smooth. The treble is not as extended as the 24 Pro, but still displays a good amount of detail. The presentation is gentler and very amenable with no listening fatigue. Staging is well done but not as expansive as the 24 Pro and just falls short in terms of layering and separation. However it is more relaxing to listen to and performs perfectly well in stock form. In a sense these two are complementary rather than rivals.
KZ AS10 Pro
The recent AS10 Pro uses the 22955 and 29689 like the original, but mid/high frequencies are handled by a dual 31736 array while the upper range is covered by a single 30019 BA. There are no BAs placed in the nozzle. The 10 Pro in stock form is quite similar to the AS16 Pro with a similar level of bass, a revealing well-tuned midrange and good treble extension. Tonality is largely neutral with a slight bright tinge in the upper mids/lower treble but, as with the AS16, use of an impedance adaptor and a copper cable bring improvements and in this form it is one of KZ’s best models. I also found tip rolling to be rewarding with a wide bore type giving the best results. The 24 Pro is brighter and more detailed, has higher resolution and a better well-controlled bass (with switches at 1100). Staging is also superior. The comments above regarding price of the AS16 Pro also apply here but the 10 Pro is preferable to the 16 Pro.
Conclusion
The AS24 Pro continues the “new direction” in tuning we have seen from KZ recently. With the latest designs like the Castor Harman, CCA Trio, PR3 and AS10 Pro, the strong V-shape profiles have become a thing of the past with now a more natural FR and timbre. The AS24 Pro continues that trend with a superb combination of accurate timbre, excellent technicalities, a high level of detail and an addictive musicality.
The packaging, it has to be said, is unacceptable at the price and the cable is not up to the standard of the IEMs. Also the nozzles are rather short which can lead to difficulties with tips. The tonality in stock form (with my source) was a little bright but I discovered that tip rolling and a hybrid cable reaped benefits. I also found that an extended burn-in was beneficial even though it is an all-BA design.
Most users will have alternative cables and tips without having to add to the purchase price and, once so equipped, it impresses with solid bass, open mids and a very extended, detailed treble. Add a wide, deep and high soundstage with excellent technicalities and you have a very complete IEM.
KZ has really “knocked it out of the park” with this model and it must be considered as the best all-BA set from the company so far, supplanting such classic models such as the AST, BA10 and CCA C16. If you are a fan of all-BA IEMs, it comes highly recommended.
