Excellent wireless range, Strong battery life at high volumes, Excellent passive noise isolation, Great vocal definition, Natural treble
Very limited sub-bass extension and slam, Odd midrange tonality, Poor headroom, Earbuds don’t fit in the case with larger ear tips
Hifiman has realised a unique product with huge wireless range and an unconventionally vocal-biased sound tuning with niche appeal.
Hifiman is a legend in the audio world. One of the first Chi-Fi hits and a pioneer of the neutral tonality earphones that are now significantly easier to come by. Still, at the time their work was revolutionary, and with continued innovation, their planar headphones and dynamic driver in-ears have been repeat hits over the years. The Sundara is a model I am especially well acquainted with as it has wormed its way into my daily rotation as one of the most natural and balanced headphones in its price class. Of particular interest is the companies new focus on wireless audio, translating their technology and expertise to newer form factors. The TWS600 was one of their first, sporting the same driver as the RE-600 with wireless functionality and a sealed enclosure. Hifiman are especially proud of their proprietary antenna design that promises 150m of wireless range. In addition, it brings some good specifications for a TWS earphone. Launched at $199 USD, the TWS600 is now commonly available at a very palatable $69. You can read more about Hifiman and Topology Diaphragm here, treat yourself to a TWS600 here and browse Hifiman’s store here.
I would like to thank Mark from Hifiman very much for providing me with the TWS600 for the purpose of review and apologise formally for my delayed impressions. All words are my own and there is no monetary incentive for a positive review. Despite receiving the earphones free of cost, I will attempt to be as objective as possible in my evaluation.
Tech Specs –
Bluetooth Version: BT5.0
Frequency Response: 20Hz – 20KHz
Weight: 5.9g (per earphone)
Play time: 5.5hrs + 33hrs
Charging time: 1hr (earphones), 1.5hrs (case)
Standby time: 110hrs
Transmission width: Up to 150m (depending upon environment)
The Pitch –
Topology Diaphragm Driver
Though perhaps most renowned for their planar headphones, Hifiman also make some terrific dynamic driver in-ears. Their most notable innovation includes Topology Diaphragm, whereby dynamic drivers are treated with a nano-particle coating. As Hifiman are able to adjust the shape, thickness and compound used, they are granted very fine control over the resulting frequency response and characteristics of the driver. It is also said to be the same driver used in the famed RE-600 which would indicate the use of a titanium diaphragm. As such, the TWS600 will be similarly sensitive to ear tip choice and acoustic output impedance and will benefit most from a narrow bore tip and deep fit.
The TWS600 is undoubtedly the most unique looking TWS earphone on the market. Its large, bulbous housings with spiral faceplate illumination create a truly otherworldly spectacle. Though entirely plastic in construction, they carry convincing density. The satin grey finish is appealing while seams are smooth albeit prominent to the eye. As such, the quality of their construction won’t challenge premium offerings anytime soon. Nonetheless, they are certainly unique and smoothly formed with an IPX4 water resistance rating meaning they will be suitable for workouts if not submergible for cleaning or swimming.
I am partial to their adoption of physical controls, one on each earpiece, that are more tactile and reliable than touch controls, especially when on the go. The actuation weight is low enough to permit multi-tap gestures but high enough to avoid accidental presses. The microphones are located on the front of each earpiece. The earphones charge via 2 gold-plated contacts that interface with the case. Due to their small size, they are prone to accumulating dirt and dust so frequent wiping is recommended to retain reliability. There are no IR sensors or other features delivering an uninterrupted audio-focussed experience.
Fit & Isolation –
Upon first inspection, the TWS600 is immediately on the larger side, and its fit is hardly low-profile as a result. Still, as they are very rounded with a thin, elongated nozzle and inset driver housing that permits the bulk of the housings to clear the folds of the outer ear, the earphones achieve a deep fit depth that ensures they don’t protrude obnoxiously. The seal is very strong, working in conjunction with dense, fully-sealed housings to create excellent passive noise isolation, some of the best in the TWS space. This is significant as their sound tuning is quite lean, so the excellent noise isolation helps to retain fidelity when listening in louder environments.
With foam tips, these would make for a great travel/commute companion. Driver flex is apparent, however, did not result in functional detriment during my testing. There are no stabilising fins, and they did require a few readjustments during a 6km run. However, never did I feel the earphones were going to drop from my ears, and I found them comfortable for listening sessions as long as their battery life would permit. These are among the more ergonomic TWS earphones I’ve tested and carry their size well due to their well-sculpted design. Still, they remain a large earphone so smaller-eared folk be warned.
Charging case –
The case shares the curiosities of the earpieces themselves, an ovoid pod that isn’t especially compact or pocketable. It has a matching satin grey finish to the earbuds, providing additional tactility and has a rubber base that keeps it firmly seated on solid surfaces but lacks wireless charging functionality despite the absence of metal. The case charges via a rear-facing USB-C port. The hinge is smooth and without wobble but lacks any spring assistance, it solidly, secured magnetically. It has a bizarre split clip mechanism to open and is symmetrical front to back making it difficult to open without orientating by the Hifiman logo.
Strangely, the battery indicator denoting the remaining case charge is located inside the case. It illuminates in 25% increments. The earbuds themselves are nestled within a precise cutout with fabric lining, a great touch. That said, the inlet is quite snug, so much so that when equipped with the large size silicone tips, the earbuds no longer slot into the case but require some force. Though clean in design, a larger inlet would have made them much easier to live with though I am fortunate to fit the medium tips just fine. The case offers an additional 33hrs of charge which is quite a strong figure in the present day.
Connectivity & Call Quality –
The pairing process is straight-forward and similar to any other TWS earphone. They have bold LED illumination that radiates across the entire faceplate. Luckily, the lights do not flash during wear so they aren’t too loud in public places. Once paired, the connection was stable and without artefacts even in crowded places such as Sydney CBD. They auto-reconnect very quickly to previously paired devices and more can be easily added by holding down the MFB’s until the LEDs alternate red and blue or simply disconnecting from a paired device, after which they enter pairing mode automatically. They can also pair independently and each earpiece houses a microphone for calls. They support true wireless stereo whereby both sides pair in mono individually to a supported source and Hifiman tells me this is the reason why Apt-X is supported as no chips supported both standards simultaneously at the time.
Indeed, codec support is limited with no Apt-X or LDAC, only AAC and SBC. Even paired over AAC to my Google Pixel 4, the experience was not ideal. Latency was especially high, useable but with overt lip-sync issues when watching videos. This is a known issue with AAC on Android, it is lower using SBC by unticking HD Audio in the Bluetooth menu and latency is lower on IOS devices. Still, it is not ideal. I also cannot speak for quality as I have no standard of comparison but under ideal circumstances both Apt-X and LDAC offer far higher bitrate transmission than AAC yet alone SBC.
On the contrary, range is outstanding as Hifiman claim, about twice that of the average TWS earphone. Where most earbuds become intermittent after crossing through 2 rooms in my house with double brick walls, the TWS600 was rock solid when crossing my entire house, around 4 rooms. This will be a great result especially when pairing with smaller DAPs such as the Shanling M0 for exercise, where the additional signal strength of the earphone supplements the weaker source and the DAP may be placed across from the body. These are challenging situations as the human body attenuated radio waves very well and signal strength is vastly reduced as a result. The TWS600’s will hold on a little longer.
Call quality through the integrated mics is average, recipients noted that my voice sounded somewhat distant but the volume was ample and my voice discernible. They aren’t the most sensitive mics for quiet conversations and, due to their orientation combined with a lack of noise suppression processing, struggle greatly in noisy environments. As such, they will do in a pinch for calls but will not be a good choice to double as a headset and audio device for mixed-use cases.
Battery Life –
Battery life is a firmly good result but no longer outstanding as modern competitors approach double-digit runtimes. The rated 5.5hrs is easy to attain in real-world listening at low listening volumes. The TWS600 offers especially high-volume output so I doubt listeners will really have to crank the volume to achieve a comfortable volume. With respect to high-volume listeners, the TWS600 will be a good choice as many TWS earphones really plummet in runtime at higher volumes. On the contrary, there is a noticeable and ever-present background hiss. It isn’t obnoxious, quite low in frequency and only mild in volume, but it does creep into quiet passages. There is also no app support so eQ will have to be set within the app itself and naturally, the setting will not stick with other devices and services.
Testing Methodology: Arta via IEC 711 coupler to Startech external sound card. Note that 7-9KHz peaks are artefacts of my measurement setup. Measurements besides channel balance are volume matched at 1K. Take this graph with a grain of salt.
The TWS600 is an absolute outlier in the TWS space, a statement accompanied by both positive and negative connotations. It harkens back to the era where neutral was lean and thin, oft associated with reserved bass. In turn and by modern standards, the TWS600 comes across as quite n-shaped with a noticeable focus on the midrange. It lacks the substantial low-end emphasis of its peers and is very dynamically flat, dead neutral in tone and diminished in fullness. There are large twin peaks in the centre and upper-midrange making vocals the focal point of their presentation. As the top-end is smooth with a reasonably neutral lower-treble, they aren’t overly bright or fatiguing.
Much like the RE-600 the presentation is clean, pitching on its midrange resolution and coherence. Of note, as this is a sealed design, unlike the RE-600, it cannot be modified to increase bass presence. You get what you get. They are sensitive to fit and ear tip selection. I most preferred the dual flange silicone tips from the RE-600 that provided a deeper fit and strong seal. The sound becomes slightly more coherent with a bit more body and less upper-midrange shoutiness to my ear. The following impressions will be with these tips installed.
Lows are laid-back and flat but also tight and imbued with that signature natural DD timbre. Sub-bass takes a backseat, there is zero pressure and very limited extension on display resulting in diminished note size and minimal slam and rumble. Mid-bass is dead-neutral, transitioning linearly into the upper-bass and lower-midrange. As such, so too is the tone neutral as well as the body of the sound. As mid-bass quantity remains, the sound is reasonably punchy, bass notes are plump if laid-back relative to the midrange and overall, the presentation isn’t shouty or anaemic. That said, it remains firmly on the lean side and is devoid of warmth which seems an unconventional choice for a commuter’s earphone.
HiFiMan are quick to tout the qualities of their topology diaphragm driver, titanium coated if it is indeed the same as that used on the RE-600. Though not as extended or dynamic as this earphone, nor as balanced overall, the qualities of this driver are the saving grace of its presentation. In particular, natural attack and decay that creates a smoother texture and increased perceived fullness. As there is high driver control, notes remain defined, translating to high detail retrieval through the low-end. Dynamics are heavily impaired due to the limited extension yet simultaneously, mid-bass is concise and punchy, helping to maintain ample pace and rhythm. Surely this is not an earphone for bass lovers or those wanting something warm and smooth. It remains a satisfying listen once adjusted, nonetheless.
As aforementioned, the tonality of the midrange is not natural, in fact, it directly contradicts conventional tuning curves. As such, coming from just about anything, this will remain an acquired taste. The timbre I do not find accurate, so even those determined to like this earphone will require some acclimatization (i.e. brain burn-in). In summary, they are not natural and the TWS600 doesn’t sound open, delicate or carry qualities associated with a pleasant midrange at a glance. Both male and female vocals sound nasal and dry with noticeable truncation. Vocals are forward and large but with neutral body and diminished clarity, a rather unique combination.
Still, once settled, we can observe some good qualities. As aforementioned, vocals are large and intimate but also layered and highly defined. As vocals derive ample body from within the centre-midrange alongside a linear bass/midrange transition, the presentation also isn’t especially thin. Similarly, despite reasonable upper-midrange emphasis, vocals aren’t strident either. In fact, articulation is quite accurate due to 6KHz attenuation that mitigates sibilance and sharpness. It is ultimately a creation for listeners averse to any kind of fatigue while prioritising vocal definition and resolution.
It’s evident that the priority of the TWS600 is its midrange yet, thankfully, the top-end has received some love too. There’s good lower-treble presence, especially around 5KHz with a 6KHz dip taking off any sharpness or aggression. The result is a smoother note attack and positioning behind the midrange but not to the extent that details are overshadowed. Lower-treble showcases sound linearity, with pleasing instrument body. Decay is natural so, in this region, treble is well-executed with good detail retrieval and texture. That said, highs roll off quite quickly beyond this, delivering an immaculate, dark and clean background but also little headroom and micro-detail retrieval.
Transient response is quite clean for a TWS earphone, especially considering the Bluetooth codecs it has to contend with. That said, extension, resolution and sparkle are surely not its strengths. Rather, the TWS600 provides an unfatiguing yet well-detailed foreground with accurate instrument timbre. Detail presentation is focussed with good contrast between background and foreground so the presentation is well-layered and composed. Not the best technical performance but a natural presentation that complements its midrange well. It just seems unfortunate that extension is so severely hampered by its limited Bluetooth codecs, especially in direct comparison to its wired counterpart.
As extension is limited, dimensions are firmly on the intimate side. Width extends a smidge beyond the head while depth is intimate due to its forward vocal presentation. That said, imaging is sound. Vocals are strongly centred with instruments to the side. As extension is limited and treble is laid-back relative to the midrange, directional cues aren’t especially sharp so the TWS600. Its strength is surely layering, all of which are defined and well-delineated. Panning is sharp with good stereo separation so the presentation remains quite engaging despite not being especially spacious or sharp.
Astrotec S80 ($70): The S80 is similarly priced to the discounted TWS600 and brings a Beryllium dynamic driver and wider codec support for the money. It has a higher IPX5 water resistance rating but slightly shorter 5hr runtime, and only 20 additional hours from the more compact carrying case. The touch controls are awful on the S80 and the fit isn’t as comfortable or stable as the TWS600 if almost as isolating with the right ear tips. The TWS600 also has better call quality.
The S80 is a more V-shaped earphone, and its midrange is more on the natural and organic side. It immediately has better bass extension and a lot more emphasis, especially through the mid-bass. It’s a little woolly, certainly not as clean as the TWS600 but driver control is very good so it retains impressive definition. Still, the TWS600 is the pacier and tighter delivery if more dynamically flat. The midrange is considerably more laid-back on the S80, and it is warmer and fuller from the low-end. It is also smoother and denser so though the lower-treble is crisper, it is not sharp or sibilant.
The S80 simply sounds more conventional, and besides vocals occupying a laid-back stage position, they have a convincing natural timbre. The high-end is thinner and sharper on the S80, more aggressive in its detail presentation. Neither have amazing extension but there’s a bit more headroom on the S80. The TWS600 meanwhile, has a more natural top-end with more accurate instrument body and decay while the S80 picks up more fine detail. The S80 has a larger soundstage, neither have standout imaging, the S80 has sharper directional cues but also less defined layers.
Lypertek TEVI ($99): Due to the TWS600’s labile price, we’ll say the TEVI is in the same price class. For the same money, it has a higher IPX7 water resistance rating and longer 10-hr batterylife. The styling is more conventional and the housings substantially smaller. Both sport tactile physical controls. The TWS600 isolates a bit more and is more stable in my ears due to the TEVI’s being if anything, too compact for me. The TEVI has wider codec support which, no doubt, is a factor in the sonic comparisons below.
The TEVI is a diffuse-field kind of tuning but with a mild bass boost, it is one of the most balanced TWS earphones I’ve heard. It has substantially better sub-bass extension and a mild emphasis in the sub-bass granting it greater low-end fullness. The TWS600 is more linear but also much more laid-back. The TEVI has similar driver control with more aggressive attack and quicker decay resulting in a similarly defined and detailed image. The TEVI’s midrange isn’t as forward but vocals are enlarged to a similar degree.
It is more balanced with the bass and treble while lacking the same nasal and truncated character, the TEVI has better vocal clarity and extension while being denser and smoother, more natural overall. Its top-end also has good lower-treble presence but has greater extension and headroom. The TWS600 has a bit more detail presence in the foreground and both are natural in presentation. The TEVI also has a dark background but has more background detail retrieval. The TEVI has a larger soundstage with similarly defined layers and it is much more separated.
RE-600S V2 ($199): The RE600S sounds quite fine even in the modern day though its tuning is clearly hitting past targets. Compared to the TWS600, it is more balanced and more conventional, it isn’t overtly natural but sounds a lot more natural. Bass extension is considerably better and the low-end has more quantity, showcasing stronger balance overall. The midrange tuning is similar but without the upper-midrange peak so it is smoother and denser, not quite so forward as well. In addition, it carryies a touch more warmth and body from the low-end.
The high-end has a small lower-treble peak which brings details to the fore. As such, the RE600 is crisper and more detailed than the TWS600 but I don’t hear it being much sharper in so doing. Meanwhile, the background is similarly dark and clean, however, there is more extension resulting in greater resolution and headroom. It has a larger soundstage and sharper, more precise imaging. Altogether, a more involving listen that would have translated very well to the TWS space, unfortunately, we have made numerous sacrifices.
The TWS600 is a strange one, that’s for sure. Yet, the more time you spend with it, the more normal it becomes. From the outset, the TWS600 was never set out to create a warm, natural and full sound. In this regard, it represents one of few alternatives to the generally more bass-focussed competition. Still, if you’re a purist wanting the most outright balanced experience, the TEVI is the clear way to go with its wider dynamic range and more conventional tuning. The TWS600 is more of an extremist, with heavy midrange emphasis and a very dynamically flat sound. What it excels with is its large, intimate yet layered vocals with excellent definition and consistent voicing between tracks. The lack of codec support and associated latency does hold the earphone back as does its awkward case design. The main caveat is also whether such a lean sound is well suited towards a form factor intended for portability. Still, I can commend, the excellent isolation and wireless range. At a now vastly reduced price, Hifiman is offering a pretty interesting product that certainly has niche appeal.
The Hifiman TWS600 is available from on Amazon (International) and Hifiman’s Store for $69 USD at the time of writing. Please see my affiliate link for the most updated pricing, availability and configurations.
Track List –
88Rising – Head in The Clouds
Chance the Rapper – The Big Day
Dire Straits – Communique
Eric Clapton – Unplugged
keshi – skeletons
Lucky Tapes – Virtual Gravity
PREP – Cold Fire
Radiohead – The Bends
Rich Brian – Amen
The Beach Boys – Surfer Girl
The Marshall Tucker Band – The Mashall Tucker Band
uncoolclub – Luvproof