Hidizs MD4 4BA IEM Review

Hidizs released a brand new multi-BA IEM, the Hidizs MD4 in late June. Designed with four custom-designed balanced armature drivers on each side. Hidizs has featured a precisely designed three-way frequency crossover, giving two BA drivers for the lower end, one BA driver for midrange, and one BA driver for the treble frequency region. The pair houses a 3D-printed acoustic tube structure.

There are two tuning switches at the back of the ear shells. They allow the users to easily adjust the output tuning bringing four different tunings in MD4. The pair can be adjusted for balanced, warm, treble enhancing, and bass-enhancing tunings.

Hidizs is well-known for its outstanding craftsmanship. The brand has designed the latest MD4 using handmade celluloid face plates, CNC machined aluminium alloy middle frame and aluminium alloy ear nozzle. MD4 looks really good. It is available in three colour options, indigo (blue), black and white.

Hidizs MD4 comes packed with a high-purity mixed hybrid cable. The cable has a 4-core braided design with 60 high-purity silver wires and 60 high-purity OFC wires tightly twisted together. It uses standard 0.78mm 2-pin connectors and a 3.5mm single-ended termination. There is also one of the best-carrying cases that I saw in this price bracket, which is handmade from premium, water-proof, sustainable polyurethane leather, designed with a magnetic clasp and iron-reinforced leather to prevent shape loss and provide maximum protection.

What’s in the box


    • Drivers: 4 BA drivers (high-frequency x1, midrange x1, low-frequency x2)
    • Frequency response: 20Hz-40kHz
    • Sensitivity: 102±dB
    • Impedance: 8Ω
    • Rated power: 3mW
    • Cable: Silver-plated OFC
    • Price: $179

I would like to thank Hidizs for providing me with the review sample of Hidizs MD4 (no affiliate link).


Let’s look at the graph first and try to understand the different sound styles achieved through dip switches. As you may first notice all 4 sound styles follow the same curve with slightly different dB levels between them. For example, the treble (blue) tuning begins with less elevation until around 1.5kHz, the bass (green) tuning begins at the top and so on. After 1.5kHz all tuning styles start to differ starting from upper-mids and try to give you the sound you like. Balanced (red) tuning has less elevation starting around 1.5kHz whereas warm (orange) tuning has the most elevation after that region. You may think why not the treble tuning has the most elevation on the highs, but then you see the least bass curve and you get the idea. Hidizs choose this kind of tuning style, playing with many points in the sound spectrum, called three-way frequency crossover, to achieve the target sound style. In short, you don’t hear what you see. The graphs are only for analysis of the sound levels, can’t tell you the final sound that occurs in your ears+brain.
I used the treble tuning for my review which suits best for my taste.There’s a slight v-shape vibe, but overall the presentation remains neutral. Resolution and clarity are excellent, and the whole spectrum shows an impressive level of definition, even at low volumes, thanks to high sensitivity and low impedance.
Lows are solid and tight with a deep rumble. Bass is there, well-defined, impactful. When some all-BA IEMs lack solid low-mids, that isn’t the case on the Hidizs MD4. Hidizs MD4 displays nicely controlled bass response and impact. For a full-BA, the result is compelling, helped by the tight seal offered by the ergonomic design of the IEM and good stock silicon tips.

Mids are clean and quick. As usual with Hidizs, mids are absolutely flawless and provide the perfect balance of sharpness and oneness. Everything seems perfectly on-point and MD4 vastly impressed me in this regard. If lows are tight, mids don’t fall short either. Vocals especially were given a lot of love and attention, and I was deeply impressed by how natural the mid-range came out. Hidizs really knows how to tune their mid-range and, in my opinion, it’s one of the most impressive features of this IEM, even if the frequency chart shows recessed mids, they sound right to the ears. Upper mids never get shouty. The tonality sounds like coming out of dynamic drivers which surprised me a lot. I liked the timbre on the mids a lot, especially on the string instruments.

Highs are engaging and smooth. The extension is great. Using a quality sound source like the Cayin Ru6 DAC and the Hidizs MD4 opens up really nicely. Highs get more air and lows gain more weight, without infringing on the voices. The seamless transition between low, mids, and highs is proof that Hidizs really did some nice engineering and tried to blend those BA drivers in the best possible way. Again without any noticeable peaks or sharpness.

The MD4 has a surprisingly clean and roomy soundstage for its asking price, much roomier than most of its competition, maybe even a level above. It has good width and depth with a nice black background. Imaging and separation are again very good with most instruments placed and imaged very well in the soundstage.

I have to add here that resolution and clarity are very good for the price. It goes to show that choosing the right driver combo and good tuning goes a long way and you don’t need to stuff 10s of drivers to achieve good resolution or boost regions of treble as a trick to bring out those details which in turn makes the sound signature sound intense, causing ear fatigue. So, the MD4 as a result is neutral-ish to warm sound signature (depending on switch config) yet resolving.


The Hidizs MD4 is a very potent IEM, surpassing some single DD competitors in the same price range for my taste. Build quality is excellent, comfort is superb, and the mature and balanced sound is very good, with impressive mids and smooth highs. With four different sound styles, it’s like you get 4 in 1 in-ear monitor that you can use depending on your mood or the genre you desire at that moment.  Paired with a quality source the MD4 behaves and scales really well. To be honest this was my first review of a 4BA IEM and I had a bias toward these all BA’s mostly because I think a single quality dynamic or planar driver is enough for a good even perfect IEM. Honestly, again, the MD4 proved me wrong, this is a different vibe, another taste that everybody should try.