64 Audio – Duo Review

64 Audio Duo


I have been a customer from 64 Audio for a couple of years now, although not always a direct customer since I also bought second hand. Still, one thing that always left a sour aftertaste in my opinion was their presentation and package.

Sure, all you really need is the monitors, the cable and some ear-tips, but their overall presentation never wowed me to be honest.

With the Duo they at least changed it up a bit. From a strict presentation point of view nothing much has changed, but 64 Audio now supplies a bigger variety of tips and a much nicer leather case.

What do I get for my money?

So what’s in the box you ask? You get their new Black Premium Cable, which has an impedance of only 0.23 Ohms and uses 26 AWG thick silver plated copper wires. This cable only comes with a mini-jack termination (aka 3.5mm).

Apart from that you’ll of course get the Duo (d’uh) and a selection of nine ear-tips. There are three sizes of SpinFit silicone tips, three sizes of regular silicone tips and three sizes of TrueFidelity Foam eartips. These are all held on a rather nice round, spider-web like plastic carrier.

And on top of that, you will get the aforementioned leather case, a shirt clip, a cleaning tool and a round sticker which you can slap on your friend’s face. Or your laptop. That’s maybe a nicer option. Your choice.

64 Audio Duo

64 Audio Duo

Build Quality

Pleasantly surprised to say the least. From knowing the Noir’s chunky trunk I expected the Duo to share similarities in the construction, but to my happiness the Duo is lighter and slimmer.

The Duo’s overall physical appearance is elegant and not gigantic at all. The black/silver mesh on top of the face plate even looks mighty nice to my eyes. One change 64 Audio made from its previous universal IEMs is how flush the top part connects to the body of the monitor. Previous products of theirs always had a small gap in between, but the Duo now features an all seamless transition from face plate to body. I like that. Not that I had issues with the Noir’s physique, but the Duo just looks more professionally made.

One issue I am still having with the Duo is the lack of lip on the nozzle. Although it didn’t happen to me since I got the Duo, there always is a chance of the ear tip being left in your ear-canal when the Duo exits. It has happened to me before with the Noir and other IEMs, and I am only waiting for the Duo to do the same, but so far I’ve been lucky.

The whole body of the Duo is made of aluminum, which I am a big fan of. I really need my IEMs to be as robust as possible. Not, that I am throwing these things around, but they sure as hell can fall from my desk and I wouldn’t want them to have dents or cracks in their shells. So big plus for that.

Overall the Duo sits nicely in my ears and I don’t get any discomfort wearing them over the course of many hours working at home.

64 Audio Duo

64 Audio Duo


For this section I have mostly used my Lotoo PAW Gold Touch and my AK120ii. I know the AK120ii isn’t a device that’s up to date in today’s market, but it served me incredibly well over the last years. And compared to other DAPs it’s very compact and lightweight, which are some of the most important features of a portable device in my opinion. But that’s not really saying anything about the sound of the new Duo, is it? So let’s get on with it.

I mentioned it before, the Duo is not really an outdoor IEM because of it’s open back design. Even as I type this, I can hear the keyboard hits coming through. That being said, I only used the Duo in the office at home or in the city. But it didn’t accompany me during transit or on walks outside, I would have been too pissed off by all the noise coming through. I used the SpinFit tips with the Duo for the entire process of listening to it.

Let’s start with the bass. And these have some serious lows. Bass is forward and definitely more than above neutral in the signature. The lows have big body and come with decent weight. They don’t sound overly hefty or thick to me, but they definitely have more body and density than most other IEMs I have listened to in the past. Actually I think in terms of body and weight these are wonderful, but for my taste there is too much bass presence overall. So for my personal preference I would like them to be a bit tuned down. As you can guess, I am not a bass-head, but those that are should find glory in the Duo.

Bass has very good definition and resolution. The Duo does reach quite deep, but does so with a slight slope where sub-bass is put behind mid and upper bass. Which gives the Duo a nicely dynamic sound in the lower frequencies. If you are a fan of Hip Hop and electronic music, you should really listen to the Duo. Because it has very good punch and drive, although at times I thought it could be a touch faster, which should be applicable for a lot of electronic genres with a high beats per minute rate.

Kick-drums and tom-toms both sound very agile and natural on the Duo, while instruments like bassoons, cellos and double bass have extremely good body and form. They still are too forward for my taste, but I can’t deny that they sound very organic and well defined.

In the last weeks I have tremendously enjoyed listening to a couple of unplugged albums. You can say about MTV what you want (I am on your side), but the unplugged sessions never disappointed me. These albums are often very well recorded and are excellent examples to listen to when you want to hear the abilities of IEMs or a headphone.

The midrange has a nice smooth sound in it. Instruments sound realistic with a slight warmth in them, to give them a more pleasant tuning overall. Mids in general are placed behind the bass-section, but then again, everything is. That however doesn’t mean that vocals or instruments don’t come through here at all, au contraire!

Deep male vocals have a dark character with a dense physique. Overall lower-mids sound just a bit darkish. What I really like about the Duo’s mids though, is how open it sounds. Often when a monitor has a bass presence like the Duo, it happens that mids are overshadowed or tuned too thick so they claustrophobic, and the Duo definitely is not closed in in any way.

The Duo wraps around your head and displays the musicians in an almost holographic way. Vocals are precisely centered between your ears, but the created stage has very good dimensions left and right. With my eyes closed I can imagine very well where each musician is standing. Even with big orchestras the Duo knows how to precisely recreate them. The Duo has good resolution for a dual driver, but don’t expect a detail monster like their 18-driver or Fourté.

Highs on the Duo have this special tia-driver character. There is good shimmer and glimmer in each treble note, but it does so without sounding too sharp or piercingly harsh. The extension up top is very good, again typical for a tia-driver treble. A point of critique would be missing richness in the high notes. I think it could be tuned just a bit softer.

To sum up the entire sound section: the Duo has a bass-forward signature with a warm and slightly darkish midrange. It creates a vast stage with excellent imaging abilities and very good resolution. But again, it’s not an earphone that you take outside. At least I won’t. Two use cases the Duo masters beautifully though is for home office calls and even watching videos. Here its open sound really comes in handy to me.

One final page and you’re done!

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


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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