64 Audio Nio Review - Hybrid Dark Horse

64 Audio Nio Review - Hybrid Dark Horse

When you enter the IEM segment of the audio hobby, one of the first things you’ll notice is that there’s a lot of ranking lists. And that’s cool! I think it establishes a baseline, so heck, I even made my own. I think it’s only natural to want to see how things stack up; to rank and classify things in the world around us.

But here’s a question that popped up for me: What if I run into something that I know isn’t the best thing in the world, but that I love to death? Do I stick with a more “objective” approach or do I evaluate from the heart - after all, what is a ranking list but subjective preference? The 64 Audio Nio is a prime example of this. I don’t think I’ve ever vibed with an IEM so well; it’s a ringer for a good deal of my target preferences. Yet, it’s not an IEM that I would quite - fear not, it’s still up there - put in the top echelons of my personal rankings. Let’s delve into why that is. 

This unit was loaned by Headphones.com for review and will be returned at the end of the review period. As always, what follows are my honest thoughts and opinions to the best of my ability.

Source and Drive-ability

  • All critical listening was done off of an iBasso DX160 with FLAC files. My musical preferences include the following: Country music, K-Pop/J-Pop, Pop, EDM, and instrumental scores.
  • I used Final Audio Type E tips and a random cable I had laying around. Yeah, I’ll talk about the “terrific” stock cable a little further down. 
  • You won’t have any trouble driving the Nio. I didn’t notice hissing on anything I paired it with, and it’s also pretty source agnostic because of 64 Audio’s LID (Linear Impedance Design) technology. 
64 Audio Nio

The Tangibles

Fairly understated packaging similar to the other 64 Audio IEMs. You open the box by simply sliding off the bottom which acts as a sleeve of sorts. Much to my chagrin, it took me several minutes to figure that out. Yeah, I know - sad hours. Anyways, here are the accessories included: 

  • Premium Leather Case
  • Dehumidifier, shirt clip, cleaning tool
  • TrueFidelity ear tips (s/m/l) & silicon eartips (s/m/l)
  • 48” Black Premium Cable
  • MX, M15, and M20 Apex modules
  • Round Sticker

The Nio are a real treat for the eyes! They’re using an abalone shell for the faceplate; it shifts colors in the light too. I’ve got to say, it’s refreshing to see 64 Audio eschew the more boring, understated aesthetics they’ve used in the past. Hey, I love their IEMs to death, but come on. There are expectations when you’re sinking this much money into an IEM. To this effect, I did note some scuffs in the aluminum shell. This is a demo unit, though, so I’ll cut them a break this time. 

But here’s a pro tip: Consider ditching the stock cable. Not only is the memory wire pesky, but the connector joints sit flush with the IEM. Unless you take great care to use both hands while adjusting the memory wire, this means you’re putting excessive pressure on the joint each time you fiddle with it. How do I know this? I own a 64 Audio U12t that I had to RMA for this exact reason. Truthfully, if this thing’s the premium cable, I’m not sure I want to know what the standard cable is like.

Gripes aside, one of the cool things that sticks out to me about 64 Audio are the small, quality-of-life technologies they’ve implemented in their IEMs. A prime example of this is their Apex, pressure-release modules. You’ve probably noticed that your ears get fatigued listening to your IEMs for longer periods. Part of that might just have to do with the fit, but it’s also because those sound waves are putting pressure on your ear drums. And while it might seem like a gimmick, the Apex modules relieve this pressure, making a notable difference in practice. Seriously - once you try Apex it’s hard to go back. 

Sound Analysis

Let’s quickly talk about the MX, M15, and M20 modules. All you really need to know sound-wise is that they mainly affect the bass. The MX significantly attenuates the bass for a near-neutral sound, while the M15 and M20 modules result in something closer to an L-shaped, bassy signature. M15 is the sweet spot for me, and it’ll serve as the basis for my sound analysis in this review. 

64 Audio Nio Frequency Response

Frequency response provided courtesy of Headphones.com. This measurement was taken using the RA0402 coupler; there is a dampening factor at around 8kHz to remove coupler resonance.


I don’t think it’s any secret that I love bass - I’ve torn apart many an IEM for not meeting my expectations in this regard. So in all fairness, the Nio’s bass might not be for everyone. It’s boosted to the point of pushing into midbass-bloat territory with the M15/M20 modules, and it does lack some finesse in the attack.

Nonetheless, I have a soft spot for the Nio’s bass; there’s something raw and dirty about it that gets me every time. A key characteristic that defines a good bass response for me is texture, a sort of micro-splicing to the timbre. On one of my test tracks, Seven Lion’s “Rush Over Me,” there’s a series of drops at around 3:40. They ripple a little slower with more grit and the Nio is more than happy to play ball. This is something that’s instantly noticeable with the Nio in bass heavy tracks - it has texture in spades. Outside of this, despite the slower attack, the decay function is spot-on with just the right amount of pull to shift gracefully into the next drop or beat. And the dynamic slam, while not the hardest hitting I’ve heard, is very natural akin to the decay function. 


Moving to the midrange, it leans toward the thicker side in terms of note-weight. From the opening guitar strings of Keith Urban’s “Kiss A Girl” to one of my favorite artists, Taeyeon and her soprano voice, I like it a good deal. And believe me, I’m pretty picky about my vocals. There’s just the right amount of meat to vocalists without diving into bloat territory, and I think the Nio has terrific macro-detail here too. Overall, while it’s not what I’d consider a natural presentation, it’s safe, lush, and complements the colored tonality nicely. 

Something else I noticed is that vocals hang slightly further to the back in terms of position. This is a trait I’ve observed on most IEMs that I’d consider to have above-average depth, such as the Campfire Andromeda 2020 and 64 Audio U12t. Whether said positioning truly qualifies as “depth” is a tricky question, but perceptually it certainly aids in projecting the image. 

64 Audio Nio


64 Audio is using a Tia driver for the highs. This is a special type of BA driver which I can’t pretend to understand all the nitty gritty of, but it’s had the lid of the diaphragm removed and been mounted perpendicular to the nozzle’s tube. So in layman's terms, by cutting out the “middleman”, this should translate to more airy, extended highs. 

As usual, this is also where I drop my disclaimer that I’m not very picky when it comes to treble. To my ears, the Nio follows a more laid-back, smooth response here. Running through some of my more treble-intensive test tracks, namely Girls Generation’s “Galaxy Supernova,” I hear plenty of mid-treble impact, but it’s clearly intended to be less fatiguing as it rolls off after around 10kHz. There is a spike at ~17kHz according to the frequency response graph; however, I don’t find the treble to be the most detailed and the Nio’s a darker IEM to my ears. It’s certainly not dead rolled-off though, and it does extend quite high (to ~19.5kHz) just playing around with an online frequency test. At the very least, I don’t think Nio's treble response will offend anyone. 

Technical Performance

First, let’s clear something up as I’ve used the word ‘cohesiveness’ interchangeably with ‘coherency’ in the past: I primarily understand coherency as being able to discern between different drivers handling their respective parts of the frequency response. This can present itself in differing note texture, timbre, and so on. Under this premise, no, the Nio is not particularly coherent. It’s DD makes its presence very much known, and the rest of the frequency response has that hybrid-esque timbre to it. 

But in a more general sense, from the textured bass to the smoother midrange and treble response, it all just syncs together very well in practice. I’m not sure how else to put it; I found myself enjoying the Nio immensely on everything I ran through it. I know, I know - we’re dangerously close to entering “getting lost in the music” territory, and it’s not something I can specifically pin-point. Part of this might have to do with the Nio just hitting my target preferences closely; regardless, I’d consider it a very cohesive IEM and certainly not lacking in that special engagement factor. 

Likewise, the way it balances its warm, timbral coloration is noteworthy. I find most IEMs like the Nio are bottlenecked in that they sacrifice technical capability. Indeed, this is most noticeable with Nio’s attack transients which take a rounder edge and lend themselves to a lack of transient hardness; the Nio’s just not the most resolving IEM at the flagship level. Still, I don’t particularly mind - the warmth takes a very pleasant hue and it’s quite the musical IEM, a worthy trade-off in my books. It certainly doesn’t hurt that pure resolution is more than sufficient in the grand scheme of things. So while this is admittedly of subjective preference, I think Nio’s got the ideal amount of warmth without heavily impacting technicalities. 

There’s also something reassuring about the way the Nio images. It doesn’t grab your attention immediately like, say, the Campfire Andromeda 2020’s out-of-head imaging, nor does the Nio have the most open, sonic-wallness stage. Rather, the Nio’s more subtle, intimate with the way it images while maintaining good positional cues. 

Unforgiving Explication 

The Nio hits my sound signature preferences very closely, but I’d be lying if I said I thought it was perfect. After all, there’s no one end-all, be-all IEM for everyone, so let me give you some reasons why this might not be the IEM for you: 

  • As I noted earlier, you might take issue with the bass response - in fact, I suspect this will be the biggest dealbreaker. The Nio has a good deal midbass-bloat with the M15/M20 modules. The MX attenuates all the bloat to my ears, but then it also seems to roll off in the sub-bass; perhaps you prefer a quantity in-between. 
  • You might prefer more treble energy. The Nio’s treble leans towards more laidback, and there might not be enough to balance out the bass with the M15/M20 modules for you. Or heck, maybe you just want a more exciting IEM.  
  • I think the Nio has very good macro-dynamics. But while it’s definitely not compressed, I can’t knock the feeling that the way it scales gradations is a bit sluggish at times, especially in the bass. Ironically enough, I noticed this most using the MX module. 

Select Comparisons

64 Audio U12t - I think this is the comparison that most people will want to see. The U12t, at least in the circles I hang in, is regarded as one of the de-facto kings of the IEM world. Sure, some might find it a tad boring, but you’d be hard-pressed to find someone who can make an argument for it being outright bad. And really, that’s the U12t’s strength: Audio’s characterized by a series of compromises; the U12t just makes the least amount of them. So let’s break-down why:

  • The U12t has the best BA bass response I’ve heard, and when it comes to control and sheer nuance, it does outclass the Nio. But it’s still not quite a substitute for a good DD, and the Nio makes this distinction all-too-clear with its more natural timbre and note density.  
  • In terms of midrange, the two IEMs are vaguely reminiscent of each other - both are very safe. The U12t’s note-weight is dead balanced; the Nio has a little more thickness to its notes. Positionally, U12t’s vocals also hang further towards the back, creating a greater sense of depth. 
  • Treble-wise, they’re similar in that I think they’re both fairly laid back. The Nio has a tad more energy because of a greater emphasis on the mid-treble; the U12t cuts out from around 8-10kHz before coming back up for more air in the highest octaves. 

Just on the basis of their respective sound signatures, the U12t is the safer option. And it stands that the U12t is the “objectively” better IEM if there ever was such a thing. The Nio simply doesn’t match the U12t’s superb technical capabilities; the U12t has an edge in resolution, detail retrieval, layering capability, plus a more open soundstage. 

But if you know what you want then I think there’s better options. After all, the U12t is something of a jack-of-all-trades. It doesn’t have a particular standout despite doing everything pretty darn well. For my preferences - mine only - I gravitate towards the Nio. I’d definitely go for the Nio if you want a more bassy, colored IEM. Either way, they’re both great IEMs, and I wouldn’t bat an eye at someone preferring one over the other. 

Sony IER-Z1R: It’s been a good while since I’ve heard this one, but I think this shootout needs to be on the record. The IER-Z1R is another resident king of the IEM world; it’s often considered the basshead’s endgame. And following a significant $300 price-cut, the IER-Z1R is out for blood:

  • Purely on the basis of their bass responses, the IER-Z1R comes out the clean winner. It has a good deal more dynamic slam and has a more drawn-out decay. The thing that’s most notable about the IER-Z1R’s bass is that it’s largely devoid of bloat - from memory, it makes the Nio sound almost uncontrolled.
  • Moving to the midrange, it’s a bit more of a toss-up. The IER-Z1R has a thinner note-weight, and it clearly struggles more with male vocals. The Nio does them better in my opinion. I do think the IER-Z1R has an edge with female vocals, but I’d have to A/B them since it’s been so long. 
  • Treble-wise, the IER-Z1R has more energy, as it follows something closer to a mild V-shape signature. I think the IER-Z1R has one of the best treble-responses I’ve heard - then again I’m not very picky - as it’s using a dynamic driver here.  

When it comes to technicalities, there’s a clear winner. I noted earlier that the Nio’s transients take a more “rounded” edge and just aren’t the sharpest. The IER-Z1R has greater transient hardness, and it’s a good deal more resolving. Soundstage also isn’t really a contest between the two IEMs; the IER-Z1R has one of the largest soundstages I’ve heard of any IEM.

If it looks like a landslide victory in favor of the IER-Z1R, well, that’s because it is - at least on paper. Personally, I find that the IER-Z1R’s presentation just isn’t as engaging in the long-term, and the magic sort of wears off. Read: It can also be fatiguing. The other issue you can expect to run into is fit. The IER-Z1R simply wasn’t designed for human ears, and I’ve seen way too many horror stories for me to consider it a safe recommendation like I might the Nio. Still, if you can fit the IER-Z1R comfortably (AKA you have blessed, chad ears), I think you know which one I recommend between the two. 

Campfire Solaris 2020 - Clocking in at a couple hundred bucks less than the Nio, the Solaris 2020 is one of the more established hybrids on the block. So how does the newcomer fare against this cult-favorite? In general, the Solaris 2020 has a more lively, energetic sound signature. At the same time, though, I can’t help but feel it’s a bit all over the place:

  • If you’ve read my Solaris 2020 review, then you’ll know that two of my biggest issues were its textureless bass and lack of decay. The Nio fixes these issues with the addition of a good deal more midbass-bloat. 
  • Midrange-wise, I noted that the Nio was thick. It is. Well, the Solaris 2002 is even thicker to the point of resulting in some nasty tonal quirks, namely upper-midrange bloat and (according to its frequency response graph) sibilance.
  • The Solaris 2020 has a much more lively, rough treble relative to the Nio’s more laidback treble. I think both IEMs have treble responses that compliment their respective signatures. 

Now to be fair, the Solaris 2020 does have quite the unique sound that I don’t think you’ll find elsewhere. Plus when it comes to technical performance, the Solaris 2020 has a clear edge over the Nio in terms of imaging capability. But the Solaris 2020 also has a good deal more timbral coloration and, frankly, it’s bordering on excessive for my tastes. I find that it significantly neuters resolution and traverses into congestion; I get “haze-fi” vibes when I listen to it. This is also why I was impressed with how the Nio balances its timbral coloration. So while the Nio’s the more expensive IEM, I’d save up a little more unless you really want the Solaris 2020. 

The Verdict

As a reviewer, I spend a good deal of time listening critically. After all, my job is to deliver information that allows you to make an informed purchase decision. But there’s something to be said for just kicking back and enjoying the music for once. The Nio lets me do that - personally, I think Nio’s sonic gold, and it’s been a good while since I’ve enjoyed an IEM so much. Nonetheless, you’ll notice that I haven’t hesitated to point out flaws here and there. And for me, that makes the Nio something of a dark horse. 

It’s not the most technical, detailed IEM at this price point. It’s not the most musical. It won’t be for everyone. But if you enjoy a bassier signature, definitely give it a shot - plus, even if you’re not much of a basshead, I think there’s merit in the Nio’s tuning with the MX module as it basically cleans up the entire bass shelf. It’s actually quite the versatile IEM in this regard, even safe, and it’ll go down in my books as yet another very good IEM from 64 Audio. So, recommended? You bet. I don’t think I’ll be getting over this one for a good while.


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