Stealth Sonics U4 – Boom, Boom, Clap!


Select Comparisons

Jomo Audio Haka (S$599)

The Haka and U4 strike similar tonal balances – a soft neutral with a lightly warm hue. But, the latter has the bolder low-end. The U4’s bass presence is fuller, gutsier and more prominent, while the Haka’s sits back for a cleaner, more relaxed profile. In terms of sub-bass extension and content, however, the Haka does deliver, so it’s no less fun when listening to genres like EDM or modern pop. The U4’s more excited mid-bass increases its musicality, while the Haka is more linear. Along with similarly laid-back upper-mids, the Haka has greater depth, while the U4 is more engaging and in-your-face.

This difference in exuberance also comes from the U4’s 5-6kHz peak. Treble notes are brighter and more rounded, while the Haka’s are wispier, softer and more feathered. This means the Haka is the more forgiving piece, while the U4 accepts being a little rough-around-the-edges in order to achieve its energy. Spatially, the Haka will sound airier due to its tighter, more compact notes. The U4’s larger images fill up the image more, but it does compensate with a sufficiently vast stage and a stable background. Imaging-wise, the Haka is slightly more coherent because of its single-armature configuration.

Nocturnal Audio Avalon (S$629)

Compared to the U4, the Avalon is a much crisper-sounding in-ear monitor with leaner instruments and a brighter sense of attack. Tonally, its transients are on the brighter side. Although this bolsters its detail retrieval and helps highlight the smaller nuances, it can get fatiguing over time. Its dynamic range may begin to falter in extended listening sessions. The U4’s warmer, thicker, more pillowy timbre will come across less revealing, but it is much more forgiving and easy on the ear. So, the Avalon is ideal if you’re after raw, clinical detail, while the U4 is if you’re after warmth, smoothness and bass.


The U4 is a refreshingly unique entry in the sub-$1000 category; one that neither shies away from a gluttonous low-end response, nor allows it to overshadow a vibrantly clear upper-midrange. Its decidedly L-shaped colouration won’t appeal to everyone. But, the riveting accents Stealth Sonics have sprinkled in through their proprietary technologies ultimately make the U4 a more compelling buy than its similarly-coloured competitors. Take into account the excellent build quality and accessories you get for the money, and that value only continues to propel. The Stealth Sonics U4 is an admirable execution of warm, forgiving and bass-y, enthusiasts of which will be hard-pressed to find a better alternative for at $500.

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About Author

Church-boy by day and audio-obsessee by night, Daniel Lesmana’s world revolves around the rhythms and melodies we lovingly call: Music. When he’s not behind a console mixing live for a congregation of thousands, engineering records in a studio environment, or making noise behind a drum set, you’ll find him on his laptop analysing audio gear with fervor and glee. Now a specialist in custom IEMs, cables and full-sized headphones, he’s looking to bring his unique sensibilities - as both an enthusiast and a professional - into the reviewer’s space; a place where no man has gone before.

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