Sony IER-Z1R Review - The Hybrid Behemoth

Review written by @Precogvision

I. Introduction 

Sony’s hybrid flagship IEM that clocks in at $1700 is something special. If you’ve spent any amount of time in some key audiophile communities, you’ll know of the praise and adoration that the Sony IER-Z1R invokes. And I should know; I’m one of its staunch proponents. I had the opportunity to hear it on loan roughly a year ago, and in the brief time I had it - a mere three days - it shot straight to the top of my personal tier list, where it’s remained since.

But a year is a long time. Since then, I’ve had the opportunity to hear dozens more IEMs, some very good ones. It’s also no secret that my stance on the hobby has matured, or simply become more critical. And believe me, I’ve even received a number of comments that I’m too harsh! Nonetheless, I’ve been itching to find out for some time now: How would the IER-Z1R fare under the scrutiny of my standards in today’s context? Let’s take a look. 

This unit was provided for review by Alan (@Netforce) of Headphones.com. Thank you! As usual, what follows are my honest thoughts and opinions to the best of my ability. 

II. Source & Driveability 

All critical listening was done off of an iBasso DX160, A&K SP1000M, and iFi Micro iDSD Black Label with lossless FLAC files. I used the stock cable and the stock tips. The IER-Z1R is a more difficult IEM to drive; however, I had no trouble powering it off of my iPhone with - heresy, I know - the Apple dongle. Hissing was a non-issue expectedly. 

III. The Tangibles

Normally, I don’t particularly care for packaging because at the end of the day, let’s be honest: After I pry out my shiny toy, it’s going straight to the closet to collect dust. But Sony has outdone themselves here, and as such, they deserve praise. This is how you do presentation and make your customer feel like they’ve gotten their money’s worth. 

The following accessories are included:

• 3.5mm and 4.4mm MMCX cables
• Sony Hybrid Silicon tips (ss/s/ms/m/ml/l/ll)
• Triple-comfort tips (ss/s/ms/m/ml/l)
• Case with storage bib and shirt clip

Expectedly, all of the accessories are of very high quality. I love that Sony has opted to include separate cables to cover the most common terminations. And there’s so, so many tips - you’ll find something that works for you. I will say that the storage bib is pretty useless (or at least I’ve never seen anyone who’s actually used it or could figure out how it works). 

The IER-Z1R is constructed of zirconium which is an interesting design decision. To be blunt: It is hefty and large to the point of which many ears will struggle to achieve an optimal insertion depth, much less comfortable listening experience. You’ve been warned. Of course, like most of the Sony stuff, the IER-Z1R’s build inspires a sense of robustness and quality you don’t get with a lot of other IEMs. The shells are emblazoned with a perlage finish, a decorative finish often used in watchmaking. 

IV. Sound Analysis 

Measurement taken off of an IEC-711 coupler. There is a resonance peak at roughly 8kHz; as such, measurements after this point should not be considered entirely accurate. 

The IER-Z1R follows something of a mild-V shaped tuning. Bass is strongly emphasized; however, largely relegated to the sub-bass regions. You already know this IEM rumbles. The midrange of the IER-Z1R exhibits a more scooped lower-midrange contrasted to a rise from 1-4kHz that dips in-between. You can expect said contrast to correspond to thinner notes; generally, these sorts of dips to frequency response are also used to impart a sense of spaciousness. Treble exhibits a bump at around 6kHz in the lower-treble, lending some energy to balance out the low-end; post-6kHz frequencies are relatively smooth. Make no mistake that this is far from being a neutral IEM. But if you listen to a lot of J-Pop/K-Pop (yes, the IER-Z1R flies best with this stuff) or enjoy the Sony house sound, then you’ll likely vibe with the IER-Z1R. 

The “Meh”.

What a way to start a review, you’re probably thinking. But you already know this is one of my favorite IEMs; I’m no dirty shill, so I say what better way to kick this off? 

The IER-Z1R’s midrange is polarizing; a testament to the fallibility of aural memory, it doesn’t sound as good as I recall. There is an audible dip from 2-3kHz which lends female vocals to huskiness. At the same time, however, the upper-midrange does lean more forward than the lower-midrange. There is some uncanny valley here, perhaps edginess, and it is particularly noticeable coming off the likes of the 64 Audio U12t and the Campfire Andro 2020 which are more smooth going through these regions. I also stand by my original sentiment about the IER-Z1R’s male vocal performance: Not bad, but by no means exceptional; this wouldn’t be my first choice with the likes of country music. 

Incoherency also plagues the IER-Z1R. I didn’t hear it the first time; nonetheless, my second listen and confirmation from trusted ears inclines me to say it exists. This is most apparent within the context of the IER-Z1R’s bass and treble contrasted to the midrange. Yes, the IER-Z1R has the best bass that I have heard. But no, it’s not perfect. There is a certain compression to it, not unlike the Moondrop B2’s bass, with which it sounds like it’s always on full-tilt (make no mistake they sound very different otherwise). In general, the IER-Z1R is also not the fastest IEM. The bass and treble skew slower in decay whereas the midrange BA takes on a slightly grainy texture, thus exacerbating a difference of timbre. This is distinct from the Sony IER-M9 which, ironically, also uses Sony’s proprietary BA drivers; the IER-Z1R sounds more dense, downwards-sloping in the midrange transients. 

And if I get real picky - you know I do - the way the IER-Z1R rides dynamic swings isn’t exactly top-tier. While we’re not talking IER-M9 levels of limp, the IER-Z1R’s dynamics are not as weighty and nuanced as the U12t’s. Something else that might not be readily apparent is the IER-Z1R’s detail retrieval. In isolation, sure, it’s good. But it’s actually not so great compared to a lot of the other IEMs that I would qualify as top-tier. The IER-Z1R only gets away with this, to a large extent, thanks to its tuning. The scooped lower-midrange, subsequent upper-midrange contrast, and lower-treble tilt inherently boost the perception of resolution.

And The Great.

Oh, and there’s a lot of it. So what’s the first thing that struck my ears when I put on the IER-Z1R again? You know, aside from the fact that they’re as chonky and frigid on the ears as ever? 

Surprisingly, it wasn’t the bass, but the IER-Z1R’s imaging. The IER-Z1R has the unprecedented ability to shape the walls of the stage, particularly in terms of height. This is something I don’t talk about often because, well, most IEMs simply don’t have it! Sure, the U12t beats it out in terms of center image distinction, and Sony’s own IER-M9 leads it in positional incisiveness. But there is nothing, and I mean nothing - at least that I’ve heard - that matches the IER-Z1R for its cathedral-like, larger-than-life presentation. In tandem with the oh-so-natural bass and treble decay, there is a sense of realism to the IER-Z1R’s imaging that cannot quite be captured in words; it excels at engagement factor and establishing the listener in the mix. 

And of course, the bass. My thoughts on the IER-Z1R’s bass probably aren’t too surprising; nonetheless, allow me to hammer home the notion: The IER-Z1R is my zenith of bass in portable fidelity. Decay, rumble, and texture, it has them all in spades. Feed it something like Everglow’s “DUN DUN,” and holy moly, the sense of sheer physicality being pushed to the drops is unparalleled; indeed, the IER-Z1R has the elusive transient density I write to no end about other IEMs lacking. But the best part? It’s nearly devoid of bloat too, hammering away at the quick, successive bassline of something like Tiffany’s “I Just Wanna Dance” with decided ease. Now, it’s still not as clean and nuanced as some BA IEMs I’ve heard - much less a planar - but unless you’re really bass-shy, something tells me you’re not going to mind. 

I don’t think I gave the treble response enough credit last time, and I’m rearing for another go.  The IER-Z1R sports a slight tilt to impact at around 5-6kHz, followed by a linear run through the crash and air regions. The timbre of the IER-Z1R’s treble is exceptional, and here, the dynamic driver being used really does shine. Transient attack with snaps and leading percussive hits is incredibly crisp, dry, and incisive. And can we talk about the reverb? Treble reverb noticeably sounds like it has broken the “walls” of the stage, lending to the IER-Z1R’s unabashedly wide staging. Stack on extension that soars to a mind-boggling 100kHz according to Sony’s specs, and indeed, it would not be an overstatement to say that the IER-Z1R’s treble sets a precedent for IEMs rivaled only by its bass response. 

V. Select Comparison

64 Audio U12t - $2000

Ah yes, a battle of the giants: How does the IER-Z1R fare against what many would consider to be the most well-rounded IEM on the market, the 64 Audio U12t? Once upon a time, I would have said that my preferences skew toward the IER-Z1R, but now I’m not so sure. It’s important to understand that these are two very different beasts:  

• The U12t has some of the best BA bass out there, but the IER-Z1R eclipses it in the timbre, slam, and decay departments. Both follow a largely sub-bass oriented shelf. 
• Whereas the IER-Z1R contrasts a leaner lower-midrange with elevated upper-mids, the U12t strays in the opposite direction with dead-balanced midrange notes. The IER-Z1R is leaner, more forward in its midrange presentation, then. 
• The IER-Z1R most closely favors the lower-treble region; it’s more aggressive. The U12t skews towards the upper-harmonics (think ~15kHz) which means listeners will find it anywhere from more laidback to somewhat tizzy. 

Intangibly, the U12t does not have the IER-Z1R’s grand, cathedral-like imaging. Staging is more compressed vertically; the U12t specializes in positional cues and center image distinction - that is, soundstage depth. And whereas the IER-Z1R leads dense and unrelenting in its transient attack, the U12t strays in the opposite direction with a pleasant softness. Indeed, some might find the U12t’s presentation too mellow; however, note that it resolves better than the IER-Z1R in terms of detail retrieval. The U12t’s dynamic range is also one of the best in IEMs, period. 

Go for the U12t if you want what is, in this reviewer’s opinion, the safest and most well-rounded IEM on the market. On the other hand, go for the IER-Z1R if you’re looking for a more exciting, aggressive presentation that sacrifices some midrange balance. 

VI. The Verdict

Ultimately, most anything is bound by context. The IER-Z1R is not perfect as I have made abundantly clear. But it unmistakably remains a top-tier IEM within the context of the hybrid IEMs that I have heard to date. In fact, I would go so far as to say it would be my hybrid IEM of choice if not for the contentious fit. 

In this vein, I am compelled to recognize that the IER-Z1R is not the safest IEM. The midrange tuning is not as balanced as it could be, and your unique ear anatomy will likely influence your purchase decision. I would highly recommend demoing the IER-Z1R for a few hours first just to make sure your ears are deemed worthy. But if you’re looking for an IEM that takes top marks in the categories of bass, treble, and imaging - when most flagships can’t even claim one of these - then this just might be the IEM for you. 

VII. Reference Tracks

• Aimer - Hakuchuumu
• David Nail - Let It Rain
• Everglow - DUN DUN
• Girls’ Generation - Galaxy Supernova
• Illenium - Broken Ones
• Joe Nichols - Sunny and 75
• Keith Urban - Defying Gravity (2009)
• Sabai - Million Days
• Sawano Hiroyuki - Best of Vocal Works Remastered (2020)
• Steve Jablonsky - Arrival To Earth
• Taeyeon - My Voice (2017)
• Tiffany - I Just Wanna Dance

-Precogvision

Watch the video review here:

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