Each of the four 64 Audio hybrids takes a slightly different approach to the midrange, either in driver configuration or tuning. Nio has the highest driver count of the lot, with six precision BA drivers for the mids and one BA driver for high-mids. Trió’s dynamic driver handles part of the midrange spectrum, along with a single precision midrange BA driver, while Fourté and Noir feature the unique Tia driver for the mids along with a single precision BA driver handling the mid-high handover. With so many different options you’d expect the midrange of all four IEMs to sound wildly different too, and while there are differences, they all share one important attribute: quality.
If I could only use one word to describe Nio’s mids, it would be lush. There’s a richness and wetness to the midrange, particularly with the M15 module, that makes female and male vocals sound both intimate and organic. With a gentle rise from 1kHz to 2kHz, the mids dip slightly before another small peak at 5kHz, bringing upper midrange vocals forward. This helps separate them from the elevated bass, though they retain the underlying warmth of the Nio’s bass blanket. While midrange detail and texture are decent, the finer technicalities are slightly subdued compared to the other hybrids, despite having the highest driver count of the lot. This can best be heard in instruments like piano, where key strikes aren’t as incisive as they are elsewhere, and guitar strings are also fuller and rounder, with softer transients.
It’s not that the Nio can’t be technical, because switching modules, Nio mX strips away much of the M15’s bass thickness and opens up the midrange, bringing it closer, technically, to the other hybrids. Vocals are pushed even more forward in this configuration, but not aggressively so, and clarity is dialed up a notch so that lyrics become more perceptible even at lower volumes. The tradeoff is some of the wetness of the M15 mids, and since highs are more dominant relative to the bass, the overall sound becomes brighter – yet far from what I would call bright. Instruments sound crisper, with more air between them, though not to the same degree as the Trió or Fourtes.
Trió’s midrange is slightly recessed, but only comparatively. Despite using a single midrange driver, Trió’s mids are audibly more detailed than Nio, likely a combination of the driver itself, the acoustic chamber, and some expert tuning. Trió’s mids also have fuller note weight, punctuated by two interesting dips at either end of the scale. Whereas both Nio and Trió dip at 1kHz, Trió’s dip is steeper, marking a sharper separation from the bass but also shaving some presence from the vocals. Where Nio pushes upper mids forward at 5kHz, Trió dips again. There’s a chasm from 5kHz until a sharp rise at 8kHz and again at 10kHz that could explain some of Trió’s brighter-leaning tendencies and occasional sibilance, and I wouldn’t be surprised if this is why I hear glassiness in some female vocals. Thankfully, as with all 64 Audio IEMs, these indiscretions are minor, and Trió benefits from 64 Audio’s tendency to tune in some transient roundness to guard against harshness.
Fourté uses a dedicated Tia driver for its midrange, which must explain the clarity and speed of its transients. Compared to Trió, Fourté has slightly more energy and fullness in its lower mids, but comes across as more neutral and less dense due to the thinner bass presence. Its upper midrange dip is shallower and comes in sooner (4kHz) than Trió, rising up again at 5kHz to give upper mids more clarity than its sibling. Fourté’s superpower, however, is its unprecedented level of midrange detail, particularly microdetails. Every flick of tongue, parch in the throat, pluck of the strings and strike of the keys is presented with surgical precision, aptly supported by an even more detailed and upwardly-elevated Tia treble. Fourté’s mids straddle the line between too much detail and more relaxed musicality, but the sheer quality of its delivery puts it, to my ears, on the safe side of that line. It does, however, make the Fourté quite unforgiving of poorly recorded material, because you’re literally going to hear every imperfection, whether you like it or not.
One of the main changes to Noir’s tuning (its driver count and types being identical to Fourté’s) is in midrange presentation. Possibly because of an elevated midbass shelf and reduced energy in the upper mids, Noir’s mids are fuller and warmer than Fourté’s, reminiscent of Nio’s tuning but with much greater detail and less organic wetness. It also avoids Trió’s glassiness, filling out any hollowness in breathy female vocals with more detail and density. Like Fourté, Noir’s mids have an incredible amount of headroom, effortlessly delivering complex instrument passages and nuanced vocals, while maintaining the same palpability and realism in more sparse compositions. Where it differs from Fourté is precision – the air between instruments not quite as black, the placement of instruments and vocals slightly less distinct, but in return it gains some musicality where Fourté leans more towards dryness and neutrality.
Katie Pruitt’s It’s Always Been You from her phenomenal 2020 debut album Expectations, is a perfect example of raw emotion mixed with both lower and sweeter vocal overtones. As the song hits its crescendo around the 4-minute mark, Nio’s (M15) rich and organic midrange comes to the fore, sacrificing the last word in detail for a fair amount of warmth, with a sweetness to the softer notes belying the passion in the lyrics. Nio (mX) is drier and lighter in tone, revealing more detail in the vocal inflections. Trió takes the detail of Nio mX and turns it up a notch, along with a hint of warmth, albeit not quite as warm as Nio M15. Fourté dials down the warmth, replacing it with even more detail, texture, air and nuance than Trió. It’s easily the most lifelike delivery, but can come across as slightly dry when compared to Nio and Trió. Noir, on the other hand, is fuller than Fourté while maintaining a similar level of detail and texture, with a hint of wetness and slightly less air. It’s also slightly more forward than Fourté and Trió, but not quite as full as Nio M15.
Neil Diamond’s Hello Again from the 1980 soundtrack to the movie The Jazz Singer, showcases Nio’s (mX) dexterity with baritone male vocals, delivering a smooth rendition of Diamond’s heartfelt vocals interspersed with well-defined piano and strings. Switching to M15 brings more wetness to the vocals, but also more bloom and weight added by the extra bass presence which makes the vocals more organic sounding. Piano and strings also sound fuller, with a more lifelike decay compared to the drier mX, but sacrificing some microdetail in the process. There’s noticeably more detail in the piano keys, strings and texture of the vocals with Trió. Though not as warm or organic as Nio M15, Trió’s midrange is not too dry here either. By contrast, Diamond’s voice loses some of its chestiness with Fourté, his delivery becoming airier, while strings and piano are played with a lighter touch and better definition than Trió. It’s also easier to pick out shuffles and other microdetails in the recording with Fourté. Noir ups the warmth, much like Nio M15, and is fuller than both Trió and Fourté. Vocals have a similar weighty bloom to Nio, being more chesty but less airy and nuanced than Fourté, though arguably more lifelike too. Piano and strings are not as clearly defined as Fourté, falling more in line with the vocals.
Holly Throsby’s What Do You Say? (featuring Mark Kozelek), from her 2017 album After A Time, is a harmonious interplay of sweet female and resonant male vocals along with well-recorded guitars and percussion effects. Two different guitars introduce the song, one in each channel, played with warmth and clarity with Nio (M15). Holly’s soft, sultry and sweet vocals have a deft touch, sounding almost ethereal in contrast to Mark’s deeper, more resonant vocals as they interplay in the chorus at the 0:40 mark. With the mX module, the intro guitars aren’t nearly as warm, and Holly’s voice is slightly drier too, but more detailed as a result. Mark’s vocals aren’t as warm either, with more edge to them. Trió injects energy and verve into the guitar intro, but also some glassiness into Holly’s vocals. She also sounds more forward in the mix, with Mark set further back, likely the result of Trió’s lower midrange dip. Fourté adds realism and air between instruments and vocals. Holly is no longer glassy, back to her sweet and sultry self, with even more nuance, and while she’s still quite forward in the mix, Mark isn’t set as far back as with Trió, his voice coming across as more airy and less chesty. Noir adds warmth into the mix, Holly sounding fuller, and Mark sounding closer, adding some real intimacy to the vocal presentation.
Miriam Stockley’s Fantasy – Sicut Cervus, from her 2006 LP Eternal, is all about vocal and instrumental harmony. Almost operatic in its delivery, Miriam’s mesmerizing voice stretches Nio’s midrange capabilities to the limit. With M15, there is an underlying bloom that almost, but doesn’t quite detract from Miriam’s chanting but does blend in with the choral cues that float around the stage. With mX, those cues become more present in the mix, but still remain well separated from the main vocal, blending in more effectively. Miriam’s voice also seems clearer and less ethereal, which actually benefits the song. Trió’s presentation is fuller than Nio mX but less bloomy than Nio M15. It’s also a fair bit more detailed. What I heard as slight distortion in the upper right channel with Nio is actually a woodwind instrument of sorts, which Trió renders more distinctly. The trailing edges of Miriam’s voice are also sweeter here. Fourté lays bare all the subtle nuances of Miriam’s voice. Without any bloom, the choral blend of male and female voices fills a larger space compared to Trió, and I can almost picture the performance taking place in an ancient stone cathedral. Noir sees the return of an ethereal air to the vocals, with more reverberation around the room. The delivery is warmer than Fourté, with some of the subtle cues less clear through the warmth, but is still more airy than Trió and more detailed than Nio.