By aspect — in detail
Consistently placed near the Harman 2019 target — a balanced, technical all-rounder with a mild sub-bass lift, not a warm/dark or overtly V-shaped set (a couple of reviewers read it as a gentle W-shape). The recurring caveat: it leans bright and lean rather than rich, and its very low 7.2 Ω impedance makes the perceived balance shift a lot with the source.
“I understood the sound of the Simgot SuperMix 4 as an IEM that follows the Harman Target”
iemsandmusic.com
“So, I would probably call the Simgot SM4 a W-shape sound signature. Better said, a bass enhanced and warm leaning W-shaped sound signature.”
Chris Love, Mobileaudiophile
“the sound signature of the supermix 4 is harmanish which is simgot signature tuning but with a tad bit emphasis on the bass”
hokagoteatimereviews, r/headphones
Measured
Tuned near the Harman 2019 in-ear target — a mild sub-bass shelf, a reserved mid-bass, and elevated upper-mids/lower-treble (pinna gain). Impedance is a very low ~7.2 Ω at 120 dB/Vrms sensitivity, so the '1/8 rule' bites: a source with more than ~0.9 Ω output impedance measurably shifts the response toward boomy/muddy, while a clean low-OI source holds the intended lean, technical balance.
Sources split on the low end. One camp hears a punchy, deep, well-controlled bass that stays in its lane and never bleeds into the mids. Another hears a reserved, sub-bass-forward tuning with a tucked mid-bass — clean but short on slam, punch and texture. The split tracks the shape (a sub-bass shelf over a leaner mid-bass) and the source: on a high-output-impedance jack it swings boomy instead.
Measured
The Harman-2019-style voicing gives a sub-bass shelf over a reserved 'tucked' mid-bass (forum measurers flag the mid-bass dip), which is why the low end reads as clean and controlled to some and as lean/short-on-slam to others. Kick attack is dry and fast. Because impedance is only ~7.2 Ω, a high-output-impedance source lifts the whole bass region and can make it sound boomy or muddy.
Where it splits
Punchy, deep and well-controlled — a clean, tactile low end with presence that never buries the mids.55%
“The bass is very impressive. It’s very well defined and controlled, yet with lots of presence, body, and richness.”
Chris, Headphoneer
Reserved and lean — good sub-bass, but a tucked mid-bass that leaves it short on slam, punch and texture.45%
“Bass is boxed in at the sub-bass end, with limited extension.”
cqtek, Hi End Portable
A genuine split. Most hear a clean, natural, well-judged midrange — neither recessed nor forward — with especially good female vocals. A vocal minority (led by the most measurement-minded reviewer) hears lean, hollow lower mids that make male vocals and instruments sound thin, with an elevated upper-mid that can tip into shout on some tracks or at volume.
Measured
A Harman-style pinna gain (elevated ~2–3 kHz) sits over lean lower mids — one reviewer measures a ~12 dB rise from 300 Hz to 2.5 kHz — so female vocals sit forward and present while male vocals read lighter or recessed. That same upper-mid lift is what tips into shout for some listeners and on certain tracks.
Where it splits
Clean, natural and present — well-judged, neither recessed nor forward, with lovely (especially female) vocals.58%
“We have very well-crafted midrange, neither too recessed nor too frontal.”
iemsandmusic.com
Lean and hollow in the lower mids — thin male vocals and instruments — with an upper-mid that can turn shouty.42%
“The first part of the midrange is so lean that it feels hollow, there is an unfilled space, a lack of physicality, of density, of body that makes many instruments sound thin, without substance, somewhat distant and lacking in strength.”
cqtek, Hi End Portable
The defining fault line. To most reviewers the treble is clean, airy, detailed and non-fatiguing, with no obvious sibilance. To a vocal minority the top end isn't clean — an un-needed edge that smears cymbals and can turn shouty, harsh or 'spicy,' especially at higher volumes or on a bright source. It is tip- and source-dependent (wide-bore tips and a clean DAC calm it).
Measured
The Harman-2019 voicing keeps the upper-mids/lower-treble elevated (forum measurers point to a presence peak around 5–6 kHz), and the piezo/planar handoff up top can add zing or smear (the measurement reviewer suspects the piezo). The same energy reads as air and detail to some and as harsh, shouty or 'spicy' to others.
⚠ vs. listeners — The elevated presence/upper-treble region is a single physical tilt described two ways: 'airy, extended, detailed' vs 'hot, harsh, shouty.' Wide-bore tips, a deeper seal and a clean low-output-impedance source push it toward the former; a shallow fit, narrow-bore tips, high volume or a bright/high-OI source push it toward the latter.
Where it splits
Clean, airy and detailed — extended without peaks or sibilance, non-fatiguing.48%
“The treble is very defined, airy, and detailed. It’s not fatiguing, has no peaks, and isn’t colored. I never heard any sibilance.”
iemsandmusic.com
Not quite clean up top — an un-needed edge that smears or turns shouty, harsh or 'spicy,' especially at higher volumes.52%
“Simgot Supermix 4 is a good burger perhaps with maybe one un-needed ingredient mucking up the upper treble.”
Durwood, Audioreviews.org
Detail
Strong consensus · 8 srcThe most agreed-upon strength. Resolution, texture and separation are repeatedly called class-leading for ~$150 — the reason the set gets recommended at all — even by listeners who dislike its tonal balance. A few note it's technical rather than warm or 'musical,' but almost no one calls it under-detailed.
“The level of detail across the frequency spectrum is exceptionally high, with meticulous articulation and impressive microdynamics.”
Chris, Headphoneer
“the level of clarity, information, description, transparency, detail, separation and scene is surprisingly good, without falling into an analytical or cold profile.”
cqtek, Hi End Portable
“Extremely detailed. Like I cannot believe they're this cheap.”
Terrible_Onions, r/iems
Soundstage
Moderate · 7 srcWidely called wide and well-arranged for an IEM — spacious and out-of-head, with a stage that's arranged rather than simply big. The common qualifier is that width outruns depth, and one or two reviewers call the width merely average, so it's a solid stage rather than a class-crushing one.
“The soundstage is impressive, with excellent instrument separation and superb imaging.”
Chris, Headphoneer
“However, it’s how the stage is arranged that makes this one special.”
Chris Love, Mobileaudiophile
Imaging
Strong consensus · 6 srcConsistently praised: precise placement and strong instrument separation for the price — the trait most owners say 'carries' the set and makes it a standout for competitive/FPS gaming. It only loosens on very busy, bass-heavy tracks.
“The stage is WIDE, and more to the point the imaging is precise.”
AddictedToTech (r/iems), via RedditRecs
“the SM4s are able to generate layering from bass, midrange and also treble, managing to separate sounds on all three axes, which is not at all common.”
cqtek, Hi End Portable
“Instrument separation is very good, nearly toe to toe with the Aful P7 i have with me.”
Terrible_Onions, r/iems
Read as energetic and lively rather than physically slammy — fast, dry transients that suit its technical bent, though the reserved mid-bass means it trades some macro-punch for control.
“the SM4 has a lot of energetic dynamism to it. This is the furthest thing from dull that you’ll hear.”
Chris Love, Mobileaudiophile
“the hit is very dry, very fast, it picks up very quickly and there is hardly any fade.”
cqtek, Hi End Portable
Comfortable and light for most, thanks to the low-weight resin shell — but it's a fairly large set with a shortish nozzle, so a minority find it bulky or hard to seal, and one owner ended up running different tip sizes in each ear. Fit (and the seal it depends on) meaningfully affects the bass.
“Both fit and comfort are excellent.”
iemsandmusic.com
“There is no forgetting you are wearing them however, so those that prefer smaller shells might find that uncomfortable for long periods.”
Durwood, Audioreviews.org
The 3D-printed resin shell with a metal faceplate looks and feels a step above the price, and the included cable is generally liked. The gripes are real, though: no balanced-cable option, and scattered QC — a faulty/intermittent cable, faceplate chipping, and a notable share of owners reporting one side dying.
“The build is actually quite nice. The Shells are made of 3D printed solid resin which feels durable in hand.”
Chris Love, Mobileaudiophile
“unfortunately I was lucky enough to get a cable with “bad contact”, the right side is causing small interruptions in the signal if I move the position.”
iemsandmusic.com
“Left Ear Bud died after less than 3 months.”
Verified owner, Amazon
Isolation
Moderate · 4 srcGood passive isolation for the class — the large, sealed resin shell blocks more outside noise than average, making it usable on transit, provided you get a proper tip seal.
“As a result of the shear size and tight fitment isolation is excellent.”
Durwood, Audioreviews.org
“The earphones offer an efficient passive noise isolation making them suitable for use the use in relative noisy environments like a subways or trains.”
Gökhan Aydın, MoonStar Reviews
“Passive sound isolation is very good.”
Chris, Headphoneer
Genuinely contested. The majority — and RedditRecs' aggregate sentiment — call it excellent value: a class-leading technical all-rounder (and gaming ace) for ~$150. A high-weight, vocal minority calls it a middling, overhyped set that needs polish, riding Simgot's name, when cheaper rivals get you much of the way.
Where it splits
A class-leading ~$150 all-rounder — big technical performance and versatility for the money.60%
“Outstanding price/performance ratio.”
cqtek, Hi End Portable
Overhyped and middling — needs polish, and cheaper sets get you there.40%
“I consider it a middle of the pack contender that needs minor polish to elevate to a top tier pick.”
Durwood, Audioreviews.org
