In-Ear MonitorOverreview

64 Audio Solo

64 Audio put a commodity planar driver in a $1,399 shell and engineered its worst habit away — and the argument about whether that's worth fourteen Chi-Fi planars has never stopped.

26 sourcesUpdated
$1,399Typical US price

Score aggregates reviewer opinions across topics.

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64 Audio Solo

The short version

What to know.

A warm, bass-boosted planar tuned in 64 Audio's house style, with the region where most cheap planars turn harsh deliberately pulled down. Sources broadly agree on several things: the treble is unusually controlled for a planar, imaging is precise, the build and the copper-mesh look are excellent, it is light and pressure-free in the ear, and it isolates far less than a normal in-ear by design. They disagree on how much weight the bass carries — full and deep, mid-bass heavy, or light and quick, a split that tracks seal and tip choice on a heavily vented shell — on whether the midrange is rich or a little thin, and on whether the stage is genuinely spacious. The sharpest split is value: on the same rigs it measures within a few decibels of planars that cost a tenth as much, and hands-on comparisons find it better but not by much, which some owners call worth it and most critics do not.

About this product

64 Audio's first planar-magnetic and first single-driver universal in-ear (sold in Japan as 64A-7433), launched in autumn 2024 at $1,399. Its Apex pressure relief is built in ("apex core"), so unlike the U4s or U12t there are no swappable modules. It took the place of the discontinued Duo, a semi-open dynamic-plus-tia hybrid, in 64 Audio's range.

The Solo was a surprise when it appeared at CanJam SoCal in September 2024: a single 14.2 mm planar-magnetic driver from a company known for stacking balanced armatures. To keep the planar from sounding like every other planar, 64 Audio added a gentle electronic treble filter and two 3D-printed Helmholtz resonators aimed at narrow bands around 5 and 8 kHz, plus its usual LID impedance flattening and a built-in, very open apex vent that lets in more of the room than almost any sealed in-ear.

Within weeks it was also at the centre of the hobby's loudest price row of the year, after a Reddit post showed what looked like the same driver selling for about $55 — the one found in $100–$200 planars like the Letshuoer S12. What the Solo sounds like is easier to agree on than what it is worth, and the reviews split on almost exactly that line.

A good fit for

  • Planar fans who are sensitive to the hot treble of most planar in-ears
  • Listeners who want precise imaging and a warm, vocal-forward tilt
  • Anyone who finds sealed in-ears uncomfortable and listens somewhere quiet
  • Buyers who weigh build quality, presentation and after-sales support alongside sound

Think twice if

  • You judge value against budget planars — several reviewers found them close in sound for a fraction of the price
  • You need isolation for commuting, flying or loud places
  • You want heavy sub-bass slam or a thick, dense midrange
  • You'd rather tune with swappable modules — 64 Audio's own U4s costs less and has them

The reviewer consensus

Agreement &
disagreement.

4 / 12topics divide opinion
buildisolationtrebletonalityimagingdetaildynamicscomfortbassmidssoundstagevalue
2 Strong agreement6 Mostly agree4 Divided opinions

Common ground6

  • Unusually controlled treble for a planar: smooth and rarely sibilant, with the usual planar glare engineered out
  • Precise imaging and clean separation in busy mixes
  • Warm, bass-boosted, vocal-forward tuning in 64 Audio's house style — not neutral

Points of contention4

  • Bass weight: deep and controlled, mid-bass heavy, or light — tracks seal and tips on a heavily vented shell
  • Midrange: rich and forward vs lean lower mids and thin male voices
  • Soundstage: genuinely spacious vs ordinary width despite the open feel

A closer listen.

12 topics · 4 divided
Left: criticalRight: positiveTighter lines: more agreement

Bass

Leans positiveDivided opinions
Reviewer sentiment11 supporting sources
CriticalNeutralPositive

Band: opinion spread · Dot: weighted average

Sources split three ways on weight rather than quality. The largest camp hears a deep, textured, well-controlled low end. A second hears plenty of mid-bass but less deep rumble than the quantity suggests, which some find thick. A smaller camp of owners hears it as light — defined but never building physical weight. Both owners in that camp tied it partly to seal: a firmer-sealing tip gave the bass more definition, though not more mass. On a shell this heavily vented, seal is a large part of the answer.

Measured

On eight IEC-711-class measurements the 20–40 Hz shelf sits within about 1 dB of the Harman in-ear target, while 100–200 Hz runs 1.6–3.1 dB above it — more mid-bass and lower-mid warmth than sub-bass emphasis. On the same rigs it carries 1.5–2.5 dB more bass than 64 Audio's U12t.

vs. listeners — A coupler always seals, so the graphs show the bass the driver makes, not what a given ear keeps. The Solo vents heavily by design, and both owners who heard it as light settled on a firmer-sealing aftermarket tip before judging it — so part of the split is likely fit rather than unit or taste.

Where it splits
deep, textured and well controlled52%

“On the other hand, you get very precise and deep-reaching bass which I personally love a lot.”

TechPowerUp (VSG)
mid-bass weighted — thick up top, shy on the deepest rumble34%

“The Solo’s bass is warm and thick, with noticeable midbass bloom”

Headfonics (Nihal)
light — defined, but it never builds physical weight14%

“The bass is there. It is audible, defined, and controlled. But it does not accumulate into mass.”

Rico's Blog (owner)
Link to this topic

The hardware

Specifications.

Checked

Design

Type
In-ear monitor
Drivers
1 × 14.2 mm planar magnetic
Housing
T6060 aluminum shell, copper faceplate mesh

Electrical

Impedance
16 Ω
Sensitivity
100 dB/mW≈ 118 dB/V
Frequency response
20 Hz – 20 kHz

Connection

Cable
Detachablecommunity-sourced: detachable cable
Connector
0.78 mm 2-pincommunity-sourced
Plugs supplied
3.5 mm, 4.4 mm balanced

Manufacturer-published figures, not measurements · from 64audio.com. Detachable cable, connector not published by the maker — community-sourced from hands-on reviews: techpowerup.com, headfonics.com.

Follow the evidence

Sources 26

1–6 of 26 sources

Read with context

Limitations & method.

As of

What to keep in mind 7

  1. A read of where the reviews land as of October 2026. Most were written in the months after the late-2024 launch, and the planar field has kept moving since.

  2. There's no meaningful owner star-average yet — only a handful of ratings exist, all five stars — so this leans on written reviews, measurements and forum owners.

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