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Driver Unit: 6mm Custom Tuned Single Dynamic
Impedance: 16 Ohm+/-15%
Sensitivity: 92dB+/-3dB at 1kHz
Frequency Response: 20Hz – 20kHz
Rated Power Input: 1mW
Max. Input Power: 5mW
Cord length: 1.36m
Plug: 3.5mm Gold Plated

Price (MSRP):  U$D 40.

Only available in silver color and mic version.

Warranty: 3 years!



·       3 pairs of single silicone tips in black color (S/M/L)
·       3 pairs of single silicone tips in white color (S/M/L)
·       3 pairs of black bi-flange tips (S/M/L)
·       1 pair of Comply Foam Tx-400 tips (M size)
·       Carrying pouch
·       Shirt clip

The accessory set is quite nice, indeed. Just to note, the black and white silicone tips only differ in color. As for the sizing, the single tips are smaller than usual, being the L size more a M size, so actually it's more like XS, S, M sizes.

Build & Design:

Build quality is very solid almost everywhere. The small 6mm driver allows the M4 to adopt a more compact design. The thin silver color housings are all metal, aluminum apparently, with a smooth surface on them. Nozzle's width is about standard, so most of eartips should fit well, and well protected by a mesh filter. Strain relief at the housings entry is not too long but it's very flexible and seems well attached.
The cable is probably the best part of the M4. Starting for the L-shaped plug, it is very sturdy and well relieved. The cable itself is twisted, not braided, and consists of 4 strands twisted in pairs; very tight and rather thick, while the upper half is softer and more flexible. While not completely tangle-free, it is still very well behaved. Y-split looks a bit small, still solid as the rest of the design, but a cable slider is missing.

Fit, Comfort, Isolation:

With its compact and straight design the M4 is a very easy to fit earphone. The eartips size is smaller than usual, so I had to use the L size even though I usually just need the M size. The bi-flange tips size is fine, but they are loose on the nozzle. Comfort is very good; the M4 is light in weight and easy to wear in both down or up cable ways. Microphonics is low thanks to the well done twisted cable, and isolation is a bit above average with the silicone tips.


The ADV.SOUND M4 has a very slight v-shaped tuning with some extra emphasis towards the treble frequencies. While still not exactly a flat neutral response it is still more balanced option than a traditional v-shaped tuning. The M4 utilizes a smaller dynamic driver and similarly to other small/micro driver based IEMs, also asks for a higher volume.

The low end has good extension and with very little slight boost on the mid-bass part for a more punchy end. For the small driver the M4 lacks in note thickness next to fuller sounding IEMs like Sony MH1, ZA Tenore, Fidue A65, but depth and layering is quite good. The low end quantity is north from neutral, but far never overwhelming. Impact is less than the M6 Pro, but trades it for better control and tightness, as the M6 sounds a bit muffled in comparison.

The midrange is slightly less prominent than the low end and bit recessed. The low end contributes to a slightly warm tonality but on the whole the M4 remains more in the cool and lean side of things. The mids can be a bit thin in body, but still much fuller than some heavier v-shaped sets such as the Xiaomi Piston (2 and 3) and Brainwavz S1. While not totally free from bass bleed, midrange clarity and resolution are very good, with a quite competent level of micro-detail when needed.

The treble is very energetic, mainly in the upper midrange and lower treble parts, giving a brighter and somehow more splashy sound. While i usually appreciate a bit of bright treble, I can't get to totally like the way of the M4 top-end is presented. Quality is quite decent on its own, not very forgiving and may sound a bit harsh, sharp and prone to sibilance sometimes, which is not something unusual on a sub $50 earphone, but there's certain unevenness and lack of control that can be annoying. While not exactly offending, it won't fall under the smooth category either, but it seems to break the whole balance with many tracks. The presentation of the M4 is not too wide but still airy enough and not congested. With the slightly thinner midrange and lack of bass bloat contribute for a more spacious sound and better separation, despite the extension on both ends isn't much above average.

Next to the old VSD1S, the M4 sounds more spacious and airy, with better instruments separation, whereas the Vsonic wins in richness and vocals texture. In terms of pure midrange quality, the RE-400 and Ostry earphones are all superior to the M4. In a certain way, the M4 is like a small version of the RHA MA750 with its slight V (or U) shaped sound, solid bass, detailed and bit dry mids and sharp treble.

Conclusion & Value:

The ADV.SOUND M4 is quite a competent contender for the sub $50 group. It features a very solid build quality for its price, with a very comfortable design and great cable. Overall sound quality is quite good, offering a slight v-shaped and lively presentation, control and detail. There's still some extra emphasis on upper regions that can take off some of the whole balance and might not suit everyone tastes. Nevertheless, the M4 offers a good value, and the 3 years warranty is a huge plus for just a $40 product.

Pros: Well built; compact and comfortable design; very good cable; 3 years warranty

Cons: better synergy with a warmer source; small eartips size; some treble unevenness