64 Audio Duo Review - Dual Driver Hybrid IEM

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64 Audio Duo Review - Dual Driver Hybrid IEM

64 Audio has recently released their new IEM the Duo, which is a completely brand new model. Prior to this, their most recent release was the U6t, which was a universal version of an IEM they’d already been selling with a custom fit for quite some time. The Duo, however, is new to everyone’s ears, mine included. While it may cost $1,199, believe it or not this is actually one of 64 Audio’s lowest priced universal models. This being said, I was still expecting impeccable quality, as no IEM in this price range should be “just ok.” So, let’s see how the Duo holds up.

64 Audio Duo Review - Dual Driver Hybrid IEM 5

What’s in the Box

- Duo Universal In-Ear Monitors

- 64 Audio Premium Leather Case

- TrueFidelity Foam Eartips (S,M,L)

- SpinFit Silicone Eartips (S,M,L)

- Silicone Eartips (S,M,L)

- Black Premium Cable

- Round Sticker

64 Audio Duo Review - Dual Driver Hybrid IEM 5

Look and Feel

In terms of physical looks, these don’t boast anything too flashy, but still feel classy. The metallic silver ring around their backing has a luxurious shine, and the grill covering the rest has a sophisticated look. Still, these don’t appear to be attempting a strong stylistic statement.

The Duo share the same shape as almost all universal models from 64 Audio have. They're sort of a halfway point between an oval and a triangle. Their curvature may look a bit simple compared to some of the highly nuanced shapes of some IEMs on the market, but they’re just as comfortable as some of the most molded looking universal fits.

64 Audio Duo Review - Dual Driver Hybrid IEM 5


The Duo is a dual driver hybrid IEM, containing one dynamic and one balanced armature. The balanced armature driver is one of 64 Audio’s signature Tia drivers, and is attributed to the high end, while the dynamic driver handles the lows. The Tia driver uses a tubeless design that is meant to reduce unwanted resonance and distortion.

The Duo also utilizes 64 Audio’s Wave Sync technology, which uses an “all-pass” filter, allowing a crossover that corrects “for time without having to change the physical distance between the drivers.” Additionally, The Duo’s face plate uses a perforated grill that opens ups the IEM to unobstructed airflow, minimizing fatigue.

The Duo have a frequency response of 20Hz - 20kHz and an impedance of 9 Ohms.



64 Audio excels at soundstages in my experience, and the Duo is certainly no exception. These come surprisingly close in width and separation to some of their much higher priced relatives in the company’s product line. However, the Duo is still not quite as far reaching as the priciest, most intensely holographic 64 Audio models, not to a fault however. The Duo seems to save its widest edges for a smaller portion of many compositions, but still kicks most competitors in its price range to the curb in terms of overall size, depth, and immersion.



The Duo has a low end that focuses on a smooth attack and filled out sub area. It’s not intensely sub dominant, but the mid point of low end elements is often a bit recessed, creating a cleaner, more groomed timbre with extra room to rumble. The Duo have a low end response similar to that of the U6t, and perhaps sharing some characteristics with the U12t, but not with quite the same pointed, hard edged attack. The punch on the Duo is more rounded, making them impactful but still easy on the ears.



The mids on the Duo felt smoothed out and warmed up. The high mid is clearly recessed a bit, while the low mids are married to the stronger low end. This balance contributes further to the very docile yet impactful sound these have. The Duo's high mids don’t feel so reduced that presence is lost from elements like vocals, strings, or keys, but there isn’t a strong bite going on. Similar to the low end, there’s a focus on cutting out any sense of harshness and prioritizing a softened edge on all fronts. Nonetheless, enough crispness is preserved to keep sounds engaging and lively.



The Duo’s high end continues its light touch, having an extremely natural feel to it. These have perhaps the most calm, organic high end of any 64 Audio IEM I've heard. While I’m not sure I’d characterize it as bright, there are some very thin pockets of shine added to bring out specific timbres in small doses, creating a dappled texture and detail boost. The Duo have a much warmer, colored high end than any other 64 Audio IEM I’ve used, and I think it works quite well. If you want more shine, there’s other options like the U12t and Tia Trio. The Duo is going to give you more of a liquid high end than an intense crispness.

64 Audio Duo Review - Dual Driver Hybrid IEM 5


I’m glad to see 64 Audio adding more to the “lower” end of its luxury price range, and clearly still putting just as much care into perfecting the product. The Duo has its own unique character that still remains versatile while adding its own perspective to sound. They have a natural but intuitive feel. The Duo does what any great IEM should: give you a new sense of closeness and intimacy with the music you love.

You can purchase the 64 Audio Duo here.

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