Kiwi Ears Quartet

Sources split on the same shelf. The large majority — most written reviews, nearly every Head-Fi and Reddit owner, and the video reviewers — hear a punchy, textured mid-bass with more control than the graph suggests and note that it is mid- and upper-bass, not sub-bass, that is boosted. A smaller but heavier-hitting camp, led by the measurement-minded ranking critics, hears the same shelf as bloom that runs into the lower mids. Both agree the sub-bass is only moderate.

Sources split almost evenly. One camp hears a lush, natural, slightly warm midrange with well-judged upper mids that never shout — several call it the quiet strength of the set. The other hears vocals recessed, veiled or fuzzy behind the mid-bass, with female voices paying more than male. Flipping switch 1 down or switch 2 up moves listeners between the two camps more than any other variable.

Sources split three ways. The largest camp calls the top smooth, safe and non-fatiguing — treble-sensitive listeners' territory. A second camp calls the same top dark, muted and short of air, and names it the set's weak point. A third hears an uneven top with a peak around 8 kHz that spoils some tracks, especially with switch 2 off. Nobody calls it bright except one outlier review.

Everyone agrees on the shape — warm, bass-first, a mild V or L that no switch position turns neutral — and splits on the verdict. The larger camp calls it a coherent, fun, musical tuning that is more balanced than the marketing implies; a smaller camp of measurement-minded critics and later owners calls it too dark and coloured, a tuning the market has moved past.

Sources split: the larger camp hears an average-to-intimate stage — in-your-head, flat in depth, crowded on busy tracks — often blaming the bass for filling the space; a smaller camp, including two of the most careful listeners, hears a moderately wide stage with good depth. Several note it opens up with switch 1 off.

Sources split, largely along the music-versus-gaming line. Most music listeners find placement precise and separation decent for the price — one calls it among the best under $200. Gamers and the ranking critics disagree: layering is vague, busy passages blur, and footsteps get buried under gunfire compared with brighter rivals.

Sources lean clearly negative, with a real minority dissent. Most call resolution average for $109 or below it — 'lo-fi', 'smeared', 'not a detail puppy', 'lack of resolution' — and several say the tuning masks what the drivers can do. A smaller camp hears surprising detail retrieval, mostly in the bass and lower mids.

Broad agreement: the isobaric pair punches. Kick drums, bass lines and macro-dynamic swings are repeatedly singled out as livelier than the price predicts, even by reviewers who dislike the tuning. The only reservations are about decay — a few hear the bass switch slowing it.

“I do find it surprisingly more dynamic and punchy that I would have guessed at the $109 range though.”

Antdroid, Audio Discourse

“The kick drum thumps with palpable physicality, while the groovy bass line receives its deserved affection.”

David Becker, Prime Audio

Near-universal praise for a very light (about 4 g) semi-custom resin shell that stays put and wears for hours, with the caveat that it is medium-large: a few reviewers report a hotspot at the concha wing, and small ears may struggle. Owners on Amazon rate comfort well and fit less well, mostly over stock tips.

“The comfort is also excellent, as I can wear the Quartet for hours without any fatigue or discomfort.”

Meldrick, Headfonics

“These fit snugly to my ear because of the fit but these do tend to create hotspots”

Berry108, Head-Fi

Reviewers rate the one-piece resin shell and its finish far above the price; the thin stock cable and the tiny recessed switches (no tool in early boxes) draw the complaints. Owners add a durability tail the reviewers do not see: on Amazon every durability mention is negative, cable quality runs four-to-one negative, and Linsoul's own reviews include a dead switch and a dead side.

“Moreover, the build quality and finishing on this IEM is as good as any IEM I’ve seen, and by any I mean IEMs that cost north of $1,000 as well.”

Guy Lerner, The Headphone List

“durability is poor with reports of cracking and constant popping off”

Amazon, 'Customers say' review summary

Mostly rated good to excellent — several call it the best-isolating set they own — with two credible dissents calling it below average. The measurement explains both: it blocks the voice band unusually hard and low-frequency rumble unusually little.

“In fact, the Quartets are the best-isolating IEMs I’ve tried thus far.”

Meldrick, Headfonics

“Isolation is below average, though the Quartet is still usable outdoors.”

baskingshark, Head-Fi

Sources split on time as much as taste. The majority — most 2023 reviews, the video class and the owner aggregates — call it an easy recommendation at $109 and the best bass all-rounder of its year. A substantial camp — the ranking critics, the IEMRanking aggregate, and 2024–26 owners cross-shopping the S08, EM6L, EG280 and Delci AE — says the tuning has been left behind and the money buys more clarity elsewhere; several suggest buying it used.