Rank #3: 64 Audio A18


But the story of the A18 starts with its modules; beginning from the bass, but working throughout the signature. For even though the primary difference between them is merely the quantity of the bass, it’s detrimental in determining the general direction of the presentation – playful, or dead serious. With the M20, the A18 sounds joyful, and exciting. The bass shifts towards the fun range, and sounds engaging. This is a bass with power. This is a fun bass. But despite the significant impact of the mid-bass, its stage remains remarkably airy – something that seems to contradict the predefined laws of performance. The airiness partially results from its quick decay, although the treble tuning certainly helps. The lifted treble provides clarity in its impact, but as a result, it isn’t the most natural-sounding mid-bass in tone; the emphasis is on power, while maintaining the clarity of the image. In addition, its definition is quite good.

Switch to the M15, and the story changes. The bass itself sounds a bit cleaner, and closer to neutral in quantity. But the main effect of taking the bass down a notch, is not necessarily the quantity of its impact; it’s in its role in determining the tone. For attenuating the bass, will automatically open up the treble. Overall, the sound becomes cleaner, while starting to lean towards analytical. This is the serious side of the A18, keeping it strictly business. It’s a more reference tuning, where clarity comes first. But this isn’t only a tuning that will appeal to the more detail-oriented listeners, as it allows flexibility over sources; with the RW AK380cu I prefer the M20 module, while I might go with the M15 for the WM1Z.

The A18’s midrange sounds clear, and clean. It’s articulated, and detailed. But even though its tonality is fairly neutral, there’s a slight hint of warmth in its midrange, powered by its bass – in the case of the M20 module. A warmer blanket over its treble energy, providing an easiness in its tone. Switching to the M15 module puts more emphasis on the articulation of midrange notes, while increasing their transparency. A more detailed midrange, resulting from the cleaner sound; though somewhat void of warmth. The emphasis is on their definition, resulting from the lifted treble. But a stimulating sound, nevertheless.

But the A18’s midrange is all about the upper-mid section: a touch of light and sparkle breathes life into its instruments. The A18’s instruments are fairly neutral in overall body; neither particularly lean nor thick. But the right type of tone or guitar can instantaneously light up the headspace, making melody-driven music particularly appealing. Despite delivering an exciting sound, the overall sound is fairly smooth. It’s close to neutral, with a slightly brighter instrument timbre – there’s an additional touch of sparkle that adds energy and liveliness to its instruments, although they aren’t completely accurate in their timbre. You can however fall back on a snarling electric guitar to provide that howl and bite, that defines their very existence. But it’s equally a type of tuning especially a violin seems to respond to, as it resonates with a beautiful clarity in its tone, while remaining smooth.

The lifted treble puts the upper midrange in the spotlight, while bringing detail to the foreground. Due to the lower treble peak, the vocal emphasis shifts towards articulation, resulting in a clear and well-defined vocal presentation. The lower midrange as a result, is somewhat laid-back. The A18’s vocal position is fairly neutral in terms of forwardness, but can on occasion lack a touch of solidity of the vocal image. The vocal size is good, but it’s not a particularly dense image; but this is strictly relative to the class leaders. In addition, their tone could be a bit warmer. There’s certainly a sweetness in a female’s voice, but a male vocal might miss a bit of emotion at times. But overall, it’s a more than engaging vocal presentation, based on its clarity and energy.

The A18’s lifted lower treble is key in shaping its signature – it benefits the precision of the sound, while providing a sense of energy. But one that’s particularly engaging to listen to as well: articulate, and rapidly quick. A technically highly proficient treble, conveying a somewhat ethereal feel. And a nice touch of sparkle gives it a musical sound, while managing to remain within tolerable limits – even for sensitive listeners. It’s a tuning accomplished by strongly attenuating the mid-treble region, following the lower treble peak. The result is a clear, but sufficiently smooth treble, even though its timbre could be a bit warmer to sound accurate.

Equally important, is its top-end extension. For the upper treble range is not only well-extended, it’s slightly more pronounced. A minor peak around 15 KHz adds a touch of brightness, while making its detail retrieval significantly more upfront – a killer combination of clarity and resolution. At times, this gives the A18’s treble notes a unique twist, a somewhat lingering decay of the overtones. A unique sense of detail, shadowing a treble note. The result is a vibrant sound, with an additional sense of realism. Taken together, an excellent treble; both in terms of excitement and performance.

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About Author

Nic is currently in pursuit of a PhD degree in social neuropsychology, while trying not to get too distracted by this hobby. In pursuit of theoretical knowledge by day, and audiophile excellence at night. Luckily for him, both activities are not mutually exclusive which helps to lighten the workload. Always on the go, Nic's enthusiasm for hi-fi is focused on all chains of the portable system: iems, cables and daps.


  1. Ray Marrero on

    An excellent review and the reason frankly I just purchased the A18. Outstanding review extremely in depth.

    • flinkenick on

      Thanks Ray, appreciate the kind words! Hope you enjoy them, let me know.

  2. IEM.Coll. on

    isine 20 sound better to my taste ..
    bigger and more natural.

  3. Lord Sinister on


    Outstanding as usual! I will make my first CIEM or high-end IEM purchase over $1K based on your reviews and something I’ve been contemplating since the days of me hounding |joker| and average_joe years ago so thank you very much. Can’t wait to see #2 & #1 reviews.

    Lord Sinister

    • flinkenick on

      Thanks for the kind words Lord Sinister!

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