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Brainwavz B400 Review: The Emptier of Wallets

Brainwavz has a long track record of building compelling IEMs for the audiophile market, mostly on the budget end of the spectrum. This has officially changed with the release of their B-series: a lineup of balanced-armature high-fidelity IEMs. Today I’ll be taking a look at their flagship offering, the B400. It features a 3D-printed build and four BA drivers.

You can find the B400 for sale here, for $200.

About My Preferences: Heads up, I’m a person! As such, these words are my opinion, and they are tinged by my personal preferences. While I try to mitigate this as much as possible during my review proccess, I’d be lying if I said my biases are completely erased. So for you, my readers, keep this in mind:

Source: The B400 was powered like so:

HTC U11 -> USB-C adapter -> earphones


Hidizs AP100 3.5mm out -> FiiO A5 3.5mm out -> earphones


HiFiMAN SuperMini -> earphones


PC optical out -> HiFiMe SPDIF 9018 Sabre DAC 3.5mm out -> earphones

All music was served as MP3 @320Kbps or as FLAC.

Tech Specs

Sound Signature

Sonic Overview:

The B400 features a gentle, though non-linear, sound signature. There’s a small emphasis in the bass, with the 100Hz range being the most notable. The midrange is fairly linear, with a mild rising of the lower-midrange and a slight recession of the upper midrange. Bass extension is very good. Treble slowly trends up in emphasis and is very cohesive. There’s no distortion on “disconnect” that one might hear on a worse-made multi-BA earphone. After letting my ears adjust, the B400’s sound signature, which is somewhat uncommon, sounded pretty well-balanced and relatively natural-sounding.

Treble: Songs used: In One Ear, Midnight City, Outlands, Satisfy, Little One

Treble isn’t peaky or washed out. It maintains clarity and precision in the majority of the songs I listened to, articulating a large number of very small details. The kicker to the B400’s treble is less its detail retrieval, and more its ability to maintain notable levels of detail without ever losing its tonality and timbre.

Rock songs really benefit from the B400’s approach to treble. High-hats and cymbals are consistently well-defined with a lively and fairly realistic timbre. Attack and decay are above average when compared to your standard dynamic-driver IEM, but on the slower side when compared to other BA IEMs. I enjoy B400’s speed though: it feels far more realistic than the clinical speed that other BA’s offer.

I had not one experience with sibilant across any song. This includes all of my worst offenders such as Satisfy and White Flag.

Midrange: Songs used: Flagpole Sitta, Jacked Up, I Am The Highway, Dreams, Too Close, Little Black Submarines

The B400’s midrange is the most polarizing component in its sound signature. The upper-midrange is recessed further than the lower midrange, and as such, can sound “stuffy” or “thick”. This was definitely my experience up-front, both when I demoed it at CanJam and when I got it in for review. But after consistently listening for about four days, my ears adapted to it and I began to appreciate it, something I really didn’t expect.

Tone aside, the recession in the upper midrange can make warmly-mastered songs a little too thick for my tastes. While these instances were rare in my music library, they did exist. But for every other song, I often found myself getting lost in the cohesive instrumental presentation that the B400’s mids so often displayed. And much like the treble, the mids have a respectable level of detail retrieval, even relative to other IEMs at this price point.

Guitars and drums sound lively and come off as naturally-sounding. String instrumentation sounded great as well, with the B400 capturing a lot of texture in its articulation. And in spite of its recession, the upper midrange blends naturally in with the treble. Electric guitars have a satisfying crunch to them and each individual instrument feels like it has a lot of sonic depth.

Male vocals don’t quite have the same presence or articulation as female vocals, though both types were still above-average in intelligibility.

Bass: Songs used: Moth, Gold Dust, In For The Kill (Skream Remix), War Pigs (Celldweller Remix)

The B400’s bass signature is super refined. The midbass has just enough of a presence to provide punch and impact but never becomes offensively prominent or overbearing. Furthermore, its blending with the sub-bass is nearly seamless. The midbass is polite and well-behaved too; it never overwhelms the midrange.

Speaking of sub-bass, the B400’s lowest frequencies are quite expressive. They extend well enough to fully articulate the bass drop in In For The Kill. And while the sub-bass is prominent enough to create rumble (even at low volumes), it is never strong enough to feel particularly visceral. Sorry, bassheads.

Packaging / Unboxing


Construction Quality

The B400’s shell is made from a 3D-printed resin. It’s easy to mistake the shell for having a rough texture when looking at it online, but don’t let the frosty tone fool you, it’s very smooth. The surface is polished, making it reflect a bit in sunlight.

The MMCX ports are set firmly in the top of the shell and they sit flush with their surroundings.

The B400 comes with two cables: one TRS cable and on TRRS cable with inline controls. The TRRS cable is pretty sturdy. Its wire is a 4-core twisted geometry wrapped with some tough plastic covering it. The Y-splitter, chin-slider, jack housing, and in-line controls are all made of a reflective metal that is fairly scratch resistant. Sensible stress-relief gives me confidence about the longevity of it as well.

The second cable is quite robust. Its wire is identical to the first cable. The MMCX jacks, Y-splitter, chin slider, and 3.5mm jack are all housed in a touch semi-matte plastic. The cable is terminated with a 45-degree jack though, which is not a very good choice in terms of drop resistance. Swapping it for a right-angle jack or straight one would better suit it in terms of durability, though given that I’d chalk this up to being used as a replacement or backup cable most of the time, I’m not really too upset about such a choice.


The B400’s nozzle is thin and the shell is relatively small. This makes it good at achieving a deep insertion which was pretty comfortable for me. I found myself wishing for slightly larger foam eartips though, as the included ones didn’t get me as solid of a seal as I was looking for. That said, swapping to larger silicone did help me out a bit.

The shell’s material is very light making it very easy to wear for long periods of time. The B400 can be worn to bed, though I don’t recommend laying on your side with it.


Inside the box you’ll find:

These accessories all feel high quality and get the job done. There’s no glaring omissions and no real revisions I feel necessary to help the accessories better suite the B400, other than the inclusion of larger foam eartips.


1: Brainwavz B150 ($70)

I’m doing this comparison simply because it’s interesting. How does the flagship B-series IEM compare to its midrange sibling? Well, they have very different sound signatures. The B400 feels much fuller than the B150, owing mostly to the B400’s recessed upper-mids. The B150 in comparison sounds a bit hollow after listening to the B400, though they both boast some pretty phenomenal detail-retrieval at their respective price ranges.

As far as build quality goes, the B400 is far and away the superior choice. From the quality of the molding on the shells to the durability of the cables, the B400 outpaces the B150. But you know, that’s really to be expected when it costs nearly three times as much. Interestingly though, I found that the B150 sealed better in my ear and remained completely comfortable for longer periods of time than the B400 did.

2: HiFiBOY OS V3 ($160)

The OS V3 makes use of driver configuration that’s quite different from the B400. Instead of using four BA drivers it goes with two BA drivers and a single dynamic driver. Furthermore, it has a very different signature from the B400, leaning more towards the B150’s style of presentation. Where the B400 has recessed upper-mids and linear lower-mids, the OS V3 has a recessed lower midrange and elevated upper midrange and lower treble. In fact, the OS V3 has a significantly more elevated treble than the B400 which does give it a more sharp tonality. Bass response of the OS V3 is also slightly weaker with more sub-bass roll-off. Overall detail retrieval is much better on the B400 though.

The OS V3 is easier to listen when coming from a traditional V-shaped IEM as its midrange generally conforms to the norm for V-shaped sound signatures.

As far as build goes, the B400 is neck-and-neck with the OS V3. Their cables, while different, each has good levels of durability. Their shells, while again quite different, are about equal in quality and fit. The B400 did come with Comply though, so I was able to get a better seal with it than the OS V3.

3: 1More Quad-Driver ($200)

The B400 and the Quad Driver are direct competitors. They have the same number of drivers, the same price, and the same target audience. The most immediately noticeable difference when comparing the B400 and the Quad Driver’s sound signatures is the midrange. The lower-mids of the Quad Driver are much less prominent than those in the B400, and the upper-mids are more linear. The Quad Driver’s midbass is also much more pronounced, washing away the lower-mids a bit. It’s a very different presentation from the B400, and one that I definitely like less. So while the B400 does sound “thicker” than the Quad Driver, it doesn’t feel like any part of the sound-signature is straight-up missing like it does with the Quad Driver.

The B400’s treble is also much better toned. It captures more details and has a more accurate timbre, especially when dealing with high-hats.

The B400’s 3D-printed shells are quite different from the Quad Driver’s metallic ones. While I think the Quad Drivers would survive a “crushing” scenario better, I don’t think they’ll fare as well as the B400 will in wear-and-tear scenarios. It also doesn’t feature removable cables; a huge no-no if you want to keep your IEMs working for several years.


The B400 is an impressive IEM when taken at face-value, and is even more impressive when taken as the very first flagship made by Brainwavz. Competitive clarity, smooth articulation, and a relatively natural tonality all synthesize the B400 into a very compelling product. For what it aims to be, you’d be hard-pressed to outdo the B400 at this price-point, and even more so whenever it goes on sale! So if you haven’t heard the B400, I suggest you go try it. You may fall in love.

As always, happy listening!



Resonance Reviews is a publication dedicated to bringing fair and rich reviews to the table while skipping the fluff that reviews usually have. We are dedicated to providing you the best in audio hardware reviews. Want to get in contact? Email us:

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