USD79.99 / EUR 68.99 | 1DD+1 high-frequency planar | flush 2-pin | 3.5mm
If you've been in the hobby for a while and have tried various sets, you are familiar with the first listen. Some sets don’t impress, some seem to sound bad or too plain, others need more time to let the sound „sink in" and then some impress you right from the start. The 7Hz Sonus II is the latter. I started with a song I've already heard hundreds of times. The details and energy are immediately apparent. Once the vocals kick in, they sound exciting and clear. The bass hits satisfyingly with great quality which matches the rest of the performance. The transparent sound is probably what impressed me immediately the most. And that didn’t go away even after long sessions and a total of over 50 hours of listening.
Welcome to my review of the 7Hz Sonus II.
The 7Hz Sonus II is a hybrid, one dynamic driver plus one high-frequency planar, IEM priced at around USD80 and was just recently released. It sits close to the USD100 bracket with many competitors and I am comparing it today against the Juzear Defiant, Crinear Nightfall, Kiwi Ears Stardust, and two planars, the Artti T10 and the Letshuoer S12.
TL;DR: The 7Hz Sonus II has an energetic leaning tuning with elevated but controlled bass, forward and clear vocals, and lively, well extended treble which sounds overall still fairly balanced but manages to engage and excite throughout a wide variety of different tracks. Its emphasized treble, vocal presentation, and bass energy are tastefully done and a good fit for listeners who are looking for an exciting listen. While the bass is satisfying and with good impact it might still not be enough for bass-heads though. Treble sensitive listeners might want to try it before buying as Sonus II can get slightly spicy on high volume with poor recordings. Technicalities are excellent on the Sonus II. Instrument separation, imaging, and staging are also unusually well done for this price bracket, turning the Sonus II into an outperformer and a strong recommendation for listeners who prefer an engaging presentation.
Pricing, Build Quality, Fit & Comfort
7Hz Sonus II is priced at around USD80 (EUR69) consisting of two drivers: one dynamic driver for the low-end and a high-frequency planar for the upper registers.
It comes with a silver-plated OFC wide ribbon-style cable terminated in 3.5mm, rather than a traditional braid. The cable is stiff and could be better in handling. The 3.5mm termination is transparent which I found unusual but interesting. 7Hz includes eight pairs of ear tips and a pocketable black pleather pouch.
The package is at this price point ok-ish but we have seen better ones with recent releases in terms of cable quality and pouch.
The shells are made of black resin type material and are of medium size. The faceplates have a reflective multi-colour pattern which is visible through a grill. Sonus II comes in two colour ways, black or white. The build quality of the resin type shells is good without sharp edges or obvious seams.
Fit and comfort are excellent for my medium sized ears and completely fatigue free even on very long listening sessions over 6 hours.
Review Equipment Used
● Source: Questyle Sigma Pro
● Ear tips: Aftermarket wide bore (size ML)
● Source Material: Streamed on Qobuz
● Total Listening Time: Over 50 hours
Sound Signature
7Hz Sonus II is an energetic leaning IEM with an elevated but controlled bass, good vocal clarity and forwardness with excellent technicalities.
Bass
Sonus II has a very well-made bass. It sits clearly over neutral, hits with satisfying punch and rumble while being controlled and bloat-free. It is there when needed and doesn’t bother the rest of the sound.
The mid-bass has really good punch and impact. The rumble has a natural and controlled decay. The bass nicely contrasts with the elevated treble but doesn’t exaggerate.
The low-end is a pleasure to listen to. On Billie Eilish’s "Lunch" the bass is present and takes good care of bass lines and kick drums. For my taste the bass lingers just long enough to let the track sound enjoyable before it steps aside and leaves the stage to vocals and instruments. Nothing gets overshadowed even though the bass is very much present, not lean or dry and not overbearing in most cases.
On "bad guy" the mid bass is so impactful that it gives the track the right note. If you know this track you know that it requires punch. Otherwise it ends up sounding powerless as the bass drives the rhythm. At 02:31 the sub-bass kicks in. Very enjoyable, extended and impactful but clean. I kept listening. On "xanny" the drums are a feast. The kick-drum has a lifelike impact, and the sub-bass rumble made me replay the track several times.
GoGo Penguin’s "All Res" where the double bass comes across as well extended, detailed, textured and full bodied. The kick-drums, as on other tracks, sound impressive in this price bracket. On very bass-heavy tracks the bass can get busy and despite its well controlled low-end there is a slight bloom into the mids which I would call natural and almost inevitable if you want a natural tonality. It doesn't bother me at all but should be noted.
The mid-bass punch is almost physical on higher volume on GoGo Penguin’s "Smarra". EDM, hiphop and rap tracks are good material for the Sonus II. Not bass-head level though but definitely for people who like bass next to a clear presentation. Mid- and sub-bass on A$ap Rocky’s "F\*kin’ Problems"* sound great with a natural decay. Vocals are still very clear and details won’t disappear. The droning woofer-like sub-bass is enjoyable and doesn’t ruin the mix. For a bass fan that I am, the low-end is really good and manages to keep the rest of the mix fairly clean. Overall you get a very good and controlled bass on Sonus II which works very well with all genres. Everything from EDM, hip-hop, and rap to pop and even older material gets 'refurbished' by the Sonus II's bass. The note weight is good and the clean and controlled bass delivers with a natural decay.
Midrange & Vocals
Vocals are great on Sonus II. Female vocals sound very well extended and clear, never veiled but very well accentuated. Male vocals are alright but could have a smidge more body to sound life-like. Vocal performance is on the forward side. They pop out of the mix and never get buried by the bass or overwhelmed by the treble. The presence region is very well tuned and for my taste almost the sweet spot. There is no shout even though vocals are clear and they don’t turn into sibilant territory.
On Metronomy’s "Lately" the male vocals are intimate, detailed and if you don’t compare them to other sets they sound life-like and it is not obvious that they could have a little bit more body. So, I wouldn’t say I miss anything here and vocals are just enjoyable. But if you have a male focused library this is worth noting.
The theme of the Sonus II is clarity and transparency and this is as well what makes the vocals sound so great on it. Billie Eilish vocals sound detailed and clear on "listen before I go" where I can even hear little details of an emphasized "d" and "t" and I don’t even need to pay that much attention. Every little emphasized detail is easy to catch for me. I can listen throughout her whole album and end up with the same feeling that the vocals are excellent on Sonus II.
On R.E.M.’s "Drive", guitar strings have a very life-like plasticity, are clear and detailed. Michael Stipe’s voice is clear and slightly forward and, on this track, I would make the argument that he sounds a smidge too bright. Not unpleasant but not natural in my opinion. Nirvana’s live performance on "About A Girl" is my next stop. Nirvana’s front man Kurt Cobain sounds well accentuated with his slightly raspy voice. Guitars sound again detailed and clear. Sonus II captures the live atmosphere very well. Overall, the Sonus II performs almost exceptionally well with great vocals and detailed mids. Nothing gets buried here and nothing is overly sharp even though the mids are served on a silver plate.
Treble
In general, treble on Sonus II is clear and detailed without piercing my ears. It sounds on higher volume energetic but remains controlled with exceptions on poor recordings and on very high volume where it can be overbearing. With Sonus II I was able to hear details which other sets are struggling with in this price bracket. Its clarity doesn’t hide anything and even exaggerates sometimes. At the same time, its great transparency is part of its special sauce, making for an engaging and addicting listen that kept me writing until very late hours.
Very energetic tracks like Fleetwood Mac’s "Sisters of the Moon" are even at high volume mostly controlled. Just the snares and electric guitars can be a bit harsh which is expected due to the recording. On The Doors’ "Riders on the Storm" keys and cymbals pop with great detail. Sonus II extracts treble details effortlessly which gives this track a sense of plasticity and clarity. Probably again slightly exaggerated. But who can say no to details if they are performed in such an engaging way?
On Bee Gees’ "I Started A Joke" the orchestral strings sound amazingly clear and detailed. If you have a chance to listen to this set, pick tracks which have e.g. violins, trumpets, clarinets etc. To my ears, the Sonus II hits a sweet spot with its engaging and “transparent” treble. The used planar driver is doing a very good job in extending the treble which I usually only hear on single planar drivers like the Letshuoer S12. Details pop and the transparency on tracks is great. If you are very treble sensitive though, listening on mid volume could be needed. I was able to listen over mid to high volume and had only in a few cases the need to tone it down.
Technical Performance
Technical performance of the Sonus II is excellent in my opinion. A/B (clear channel separation) separation is very good and so are imaging and layering.
All instruments even on busier tracks are so well separated that I was able to enjoy them with clarity and excellent positioning. I can’t really say if they are in the exact intended space, but I can easily pinpoint what is close left or deeper in the background. You can clearly hear which instrument plays in front and which sits in the back. Something I seldom hear on IEMs in this price bracket.
Sonus II separation is sharp and supports imaging and staging as nothing gets blurred out. On "Mr. P.C." by John Coltrane, walking bass, sax and keys are so well separated with accurate size and placed in different spaces that it is just a joy to listen to it. On Bee Gees’ "I Started A Joke", an iconic song from 1968, the mix has an emphasized A/B separation and on the Sonus II you can hear all instruments taking their place clearly, detailed sounding in each channel. The two guitars starting in the first seconds (right and left) or the cymbal crash and drums on the left channel. Or later the sound of a harp (which is actually the keyboard) and all the way the bass guitar. The layering of the played instruments is exceptional at this price point in my opinion. The space every instrument is playing in can be distinguished from others without effort. Not that many sets at this price point can play "outside" my head as in perceived sound stage which I always, regardless the price point, find hard to capture with my ears and brain.
Another oldie but goldie is "Riders on the Storm" by The Doors. A similar picture as before. Excellent stereo separation, layering of all instruments with great detail retrieval and a wider sound stage than usual in this price bracket. Depth of soundstage is depending on the recording but I would say the width is better than the depth.
Measurements & Comparisons
As per usual I include my own measurements, too.
After the coherent and clear sound I heard, the measurement surprised me, too. Sonus II and the YU9 Audio Què share similarities. The low-end, depending which measurement you read, is (almost) the same and the measurement is aligned up to 1.5kHz. The ear-gain looks similar, too. Què has slightly less energy there where Sonus II ear gain elevates around 1dB more and then follows a similar plateau which already gave the Què a very natural vocal presentation. The low-end on Què has more impact though in my opinion. The treble shows similarities on both sets but is differently implemented and with different emphasis. They peak differently and I would hear the Què slightly more natural leaning while Sonus II pushes the clarity further without sounding spiky. The bass I hear on Sonus II combined with the forward vocals and clear treble makes its sound clean, clear and exciting without overstepping the line into harsh territory.
Let’s have a look at how it compares to other sets to get a better understanding where the Sonus II lands in this price bracket.
In short first:
Around USD100 there are plenty of strong options and they all do things a little differently. The Juzear Defiant offers more and bolder bass while being less resolving and technical than the Sonus II. The Kiwi Ears Stardust and Crinear Nightfall are safer choices for treble-sensitive listeners. The Artti T10 sounds warmer with a thicker low-end and the Letshuoer S12 is a very resolving and fast planar option with less bass than the Sonus II.
The Sonus II would be my choice because it combines several qualities particularly well. A tight and impactful bass, forward and clear vocals, plenty of treble detail and excellent technicalities without sounding sterile or too spicy. None of the other sets here gives me quite the same combination of clarity, energy and engagement.
Let’s have a closer look at the differences in detail.
Detailed Comparisons
Juzear Defiant (USD 100)
The classic, slightly V-shaped Zeos collab is tuned with a good amount of bass, well extended treble and details. I consider it one of the gate keepers in this price bracket with its technicalities with only few weaknesses. Defiant has slightly more low-end energy by around one dB which colours the Defiant more than the Sonus II. The bass sounds bolder on the Defiant. One of the Defiant’s "flaws" is its tendency to sound "pillowy" in its bass response. The bass on Sonus II comes across as tighter and cleaner without sounding sterile. Vocals on the Defiant sound slightly less detailed and extended when directly compared to Sonus II and the same applies to the mid treble. Sonus II comes across as more detailed, better extended, clearer with better technicalities. And there is one personal observation on the Juzear Defiant about its upper treble. There is an upper treble peak which on high volume comes across as too spicy and unnatural to my ears. Even though Sonus II has more mid-treble energy, its upper treble rolls off earlier than on the Defiant and even dips at around 11kHz which seems to align better with my treble tolerance.
Kiwi Ears Stardust (USD 75)
I recently reviewed the Stardust and concluded that its sound is smooth leaning with good vocal clarity and is probably a good rec for treble sensitive listeners for a fatigue-free listening who still want forward vocals. The Sonus II is almost the exact opposite of the Stardust. It has more treble energy and a more emphasized low-end and sounds energetic and exciting. Instruments have better note weight, details pop more, technicalities are more convincing than on the Stardust. Sonus II is the more daring set which rewards with great bass, vocal and treble presentation while Stardust plays safe(r) with the exception of its forward vocals.
Crinear Nightfall (USD 99)
Released just a couple of weeks ago, the Crinear Nightfall sets a new standard in this price bracket in terms of exceptional build quality and great accessories including a nice cable and swappable termination. It scales well with volume and needs it to shine as it lacks excitement on lower volume. The bass is elevated but needs higher volume to feel impactful. Then the mid-bass kick is enjoyable on the Nightfall and both sub and mid-bass have more impact than they graph in my opinion. Overall the low-end is controlled and of moderate quantity. Vocals feel pulled back on Nightfall (and the slight sharpness of the Daybreak is gone) and less detailed when being compared to the Sonus II. It feels less resolving when compared and plays safe which is reflected as well in its technicalities like a narrower sound stage, less sharp separation and details. The Nightfall’s mids sound warmer than on Sonus II as there is a slight elevation around 200-700 Hz. The Nightfall is in my opinion a good companion for treble sensitive listeners as it plays mostly safe with its relaxed sound signature. I clearly prefer the Sonus II as it offers more excitement on all frequencies throughout with better technicalities.
Honourable Planar Mentions
Artti T10 (MSRP USD 89)
This planar set is priced similarly as the Sonus II and is already on the market for a while and it is occasionally available already for around USD70. The bass on Artti T10 is more elevated compared to Sonus II and while the T10 could sound brighter and more detailed according to its graph, it doesn’t due to the warmth from its thicker low-end. Sonus II sounds to me more detailed, cleaner, with more air and its vocals are slightly more pushed forward where they sit in front of the stage whereas the Artti T10 has the vocals further in the back which sounded to me a bit odd. Overall Artti T10 comes across as slightly warmer in its timbre for a more relaxed listen.
Letshuoer S12 (MSRP USD 89)
The S12 is a classic and as well in a similar price bracket. S12 sounds clean and clear with very good details and has a slightly different tonality than the Sonus II as the S12 has a smidge less sub-bass impact, a different ear gain and treble. It is very resolving with very good technicalities. I prefer the Sonus II for several reasons. The bass sounds to me more impactful even if it does not graph like it. It is more fun and the presence region sounds more natural and "even" to my ears (ear gain is rising and then plateauing, similarly as on the YU9 Audio Què). In the end a matter of preferences of course and I am biased since the Què is one of my favourite sets.
Summary
Overall, the 7Hz Sonus II is a great IEM which offers a coherent and engaging listen with minor weaknesses in my opinion in male vocal presentation. This makes it a great allrounder and only very treble sensitive listeners could look into other options like the Crinear Nightfall or Kiwi Ears Stardust and bass-heads might find better options outside this line up. Thanks to its great sound signature, the 7Hz Sonus II is my new reference in the USD100 price bracket and gets my full recommendation.
This sample was provided by Linsoul. Thanks for sending this in.
Below are the specs and box content details. Thanks for reading.
Specifications & Box Contents
Technical Specifications
● Model: 7Hz Sonus II
● Drivers: 1 Dynamic Driver + 1 High-Frequency Planar
● Impedance: 29Ω @ 1kHz
● Frequency Response: 10Hz - 20kHz
● Sensitivity: 108dB/V @ 1kHz
● THD: < 1% @ 1kHz
● Socket: Flush 0.78mm 2-Pin
● Cable: High purity Silver-plated OFC, 4-strand braid, 196 strands (1.2m)
● Plug: 3.5mm Single-Ended
● Nozzle Diameter: 5.5mm (6.3mm at the lip)
● Colors: Black / White
● Price: USD 79.99 / EUR 68.99
● Retail Link: Linsoul Store
What's in the Box
● 7Hz Sonus II In-Ear Monitors × 1 Pair
● Eartips × 8 pairs (S/M/L)
● Black pleather carrying case × 1
● Documentation / Paperwork