64 Audio – Duo Review

64 Audio Duo

In this article we review the $1,199 USD 64 Audio Duo IEM


Disclaimer: 64 Audio kindly supplied the Duo for this review. The Duo stays 64 Audio’s sole property. It is selling for 1,199 USD.

64 Audio

In our corners 64 Audio shouldn’t need an introduction anymore. But that doesn’t mean, that we won’t give you a quick run-down of their history nonetheless.

64 Audio is an American brand that produces custom and universal fit In Ear Monitors. Their product range goes from their most affordable A2e all the way up to the very high end A18t/s.


64 Audio has been around the audio scene for over eleven years already. They began their journey as 1964 Ears but have renamed themselves to 64 Audio in the meantime.

The company was founded by Vitaliy Belonozkho and during the process of the company’s success many brothers of the Belonozkho family have joined Vitaliy. Although it has to be noted, that some of them also have left the brand in order to realize their own visions.

Since their creation 64 Audio has kept pushing the envelope with new technologies. They introduced their tia drivers, which are openly radiating balanced armature drivers. Aside from that, they also introduced LID (Linear Impedance Design) and Apex. LID basically sets an almost linear impedance curve throughout the entire frequency range, while Apex helps mitigate ear-fatigue by simulating a secondary ear-drum. This is an open module that eliminates pneumatic pressure that builds up in an otherwise closed room.

64 Audio’s main focus clientele-wise however is not necessarily audiophile based. They work with many renowned artists, such as Alanis Morissette, Beyonce, John Mayer, Nathan East, Black Eyed Peas or Bon Jovi. Just to name a few.

Product Overview

With that in mind it makes abundant sense, that 64 Audio provides most of their products as custom fit options. Personally, I love custom IEMs and even have the A18t and A18s in my own repertoire of CIEMs.

Their products are classified on their website for stage, for studio and for audiophile. Their most affordable option is the A2e, which is a dual driver custom only IEM that sells for 499 USD. In their portfolio you will also find the A3e (699 USD), the A4t (t indicating it uses a tia driver; 999 USD), the A6t (1,299 USD), the N8 (1,699 USD), the A12t (1,999 USD), the A18t (2,999 USD) and the A18s (2,999 USD).

Apart from their custom range (see above) they also offer some universal models. Like the U6t (1,299 USD), the Nio (1,699 USD), the U12t (1,999 USD), the U18t (2,999 USD), the U18s (2,999 USD) and the all-tube-less Trio (2,299 USD) and the Fourté (3,599 USD).

Newest member of the family is the Duo, which sells for 1,199 USD.

By the way, you can get pretty decent discounts for their B-stock inventory. So be sure to check that out regularly: https://www.64audio.com/pages/b-stock

64 Audio Duo

64 Audio Duo


The Duo is 64 Audio’s latest IEM creation and the first of theirs to use an open back design. Like the Trio, Fourté and Noir it makes use of their tubeless designs, where the drivers are placed in special chambers in which they radiate.

Lets take a quick look at the technical side of the Duo.

What’s to know?

It’s hybrid design, that uses a 9mm dynamic driver for lows and mids as well as a tia high driver. Pretty simple. It has a sensitivity of 98 decibels, which is not exactly low for an in ear. That means you will have to crank up that volume a little further to reach your nominal listening levels. Although I don’t advise you to do that. Hearing is important.

The Duo has an impedance of just 9 Ohms, but remember due to LID this is a rather flat 9 Ohms. So you shouldn’t run into any impedance miss-match situations where the high output impedance of your source will skew away the Duo’s intended signature.

With its open back nature, the Duo only is rated at -12dB isolation. So there will be more than usual sound leakage. I really don’t recommend wearing these on your daily commute. The amount of noises coming in is way too high for a busy subway or vibrant street-actions. Another first for 64 Audio with the Duo is the use of Wave Sync. Their website has the following to say about it:

“Due to the high crossover point between the two drivers, Wave Sync was developed to ensure coherence; another industry first. By using a type of “all-pass” filter, we’re able to introduce a crossover while correcting for time without having to change the physical distance between the drivers.”

The Duo sells for 1,199 USD straight on 64 Audio’s website.

Continue on Page 2!

Page 1 – Brand history and technical details
Page 2 – Packaging, Build and Sound
Page 3 – Comparisons & Conslusions

4.5/5 - (137 votes)

Been into music and sound since he was a little brat, but spent his profession in a more binary field making things do what they were supposed to do. Ultimately just another dude on the internet with an opinion, into which you shouldn't put too much thought.

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