A dual-dynamic IEM that measures within a decibel of the same curve on every rig that has held it: a ~6 dB sub-bass shelf, a lower-midrange tuck, a smooth ear-gain plateau a couple of decibels under Harman and a treble that stays well under it. Reviewers broadly agree that this is a mature, accurate, fatigue-free tuning that needs no EQ, that the accessory pack is generous, and that isolation is good. Beyond that the record splits, sometimes sharply: on whether the bass is satisfying or the wrong amount (lean to some, thick to others), on whether the treble is smooth or rolled-off, on whether the technicalities — detail, soundstage, imaging, transient snap — are 'benchmark for the price' or 'pretty mediocre', on whether the fat, long nozzle is fine or unwearable, on whether the shell lasts, and on whether the whole thing was ever as special as its launch made it sound. A tuning benchmark with a durability tail and a fit lottery, not a technical giant-killer.
About this product
The May 2023 dual-dynamic (10 mm + 7.8 mm) IEM tuned by Crinacle to his IEF Neutral target plus a ~5 dB sub-bass shelf, shipped with a 10 Ω bass-boost adapter. Launched at $54.99; the maker's price is $64.99 as of September 2026 (some dealers still list $54.99 on back-order). Not the original 2022 Truthear x Crinacle ZERO (the brighter, bassier 'Blue'), nor the 2025 Zero:BLUE2, and not the 1DD+3BA Hexa or the warmer Pure.
The Truthear x Crinacle ZERO:RED arrived in May 2023 as the sequel to the wildly popular original ZERO — the same unusual twin-dynamic-driver layout, a 10 mm woofer crossed to a 7.8 mm driver in the same resin shell, retuned by Crinacle toward his own IEF Neutral target with a cleaner sub-bass shelf, a reworked crossover for lower distortion, and a 10 Ω adapter in the box that dials the bass up on demand. At $55 it was pitched — and quickly received — as the new default answer to 'what's the best IEM under $100?'
Three years on it is still the set new buyers are pointed at, still the set other budget IEMs are graphed against, and still an argument. Fifty-five measurement rigs agree on the tuning almost to the decibel; the reviewers who heard it agree far less on what that tuning is worth, whether its bass is lean or thick, whether its safe treble is control or a veil, and whether the shell fits a human ear. Plenty of praise to average; plenty of disagreement to map.
