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THIEAUDIO has spent years building trust and a following by packing serious tuning obsessions into attainable gear. Since launching under Linsoul and rising fast on the strength of models like the Monarch line, the Chinese brand has not been subtle in its ambitions to offer boutique-level configurations without boutique-level pricing. While THIEAUDIO has launched compelling kilobuck+ flagships, the sweet spot has been mid-fi products for obsessives on a budget. And the Hype 4 MKII IEM and Cypher semi-open headphones feel like a sharper extension of that focus. At $399 each, they arrive in very different shapes but chase similar ends: sound with more poise and precision, but with just enough mischief left in it.
The build
An update to a 2023 forums favorite, the Hype 4 MK II is a six-driver hybrid in-ear monitor rebuilt from the ground up in an enclosure machined from durable anodized aluminum. Underneath an iridescent inlay are the brand’s latest IMPACT2 dual-8mm sub-bass system paired with four updated Knowles balanced armatures. The Cypher, meanwhile, is a new 50mm dynamic-driver wired headphone built from aerospace-grade aluminum, stainless steel, lambskin, and enough confidence to debut at a CanJam and act like it belongs there.
The Hype 4 MKII’s IMPACT2 low-end system features composite-diaphragm dynamic drivers in a proprietary pneumatic acoustic chamber, then hands the rest of the spectrum to a stack that’s pure modern hybrid maximalism: two RAB-series drivers for the lower mids, an ED-33465 handling upper mids and lower treble, and a RAD-33518 ultra-tweeter pushed up near the nozzle for extra extension. On paper, that adds up to a four-way crossover, six total drivers, an 18-ohm load, 101dB sensitivity at 1 kHz, and a quoted 5 Hz to 22 kHz frequency response. In practice, it’s easy to drive from ordinary sources, but tuned with the kind of fixated care that makes every sonic edge feel just as filed and fitted as the physical casing.
Accompanying the IEMs in the small rectangular hard case, you’ll find a detachable modular cable made with 6N ultra-pure monocrystalline copper and accompanied by easily swappable 4.4mm balanced and 3.5mm unbalanced plugs. Additionally, there’s a selection of silicone and memory foam ear tips, though I ended up swapping to a pair of Divinus Velvet Wide Bore and doing most of my listening from FiiO M27 and iBasso DX340 [AMP15] DAPs.
The Cypher uses a newly developed 50mm dynamic driver built around a 20-core N45 magnetic array, a semi-crystalline polymer-and-rubber composite diaphragm, and a high-tension copper-aluminum composite voice coil. The shell is equally intentional: swiveling CNC-machined single-block aerospace-grade aluminum earcups, a stainless-steel headband with a carbon-fiber-like surface treatment, a supple suspended lambskin strap with fabric-covered segmented padding on the underbelly, velour-and-memory-foam magnetically mounted pads, and a final weight of 411 grams.
The grille’s geometric weave has a fabric-like appearance with an almost Meze Audio-lite industrial elegance. The Cypher is rated at 32 ohms, 96dB sensitivity, and 20 Hz to 20 kHz—easy enough to run off a laptop, though clearly happier when given a little dignity upstream, which is why I tried them with the TEAC UD-507/HA-507 stack and a Schiit Audio Jotunheim 3.
Included in the surprisingly low-profile leatherette carrying bag [the Cypher pivots flat] is a detachable 1.5-meter (4.9 ft.) braided cable with a nylon-braided exterior and 3.5mm/6.3mm gold-plated connectors. And if you want to upgrade to a balanced option, the Cypher’s dual mono inputs are aftermarket-friendly.
The sound
The Hype 4 MKII is an extroverted IEM, but not a messy one. For many familiar with the fun-tilted original, it will be surprisingly clean and controlled. In the low end, adrenaline’s sparks have been exchanged for dopamine’s slow burn. Bass still hits with a tight, piston-like punch that gives kick drums a beveled edge and synth lines real body. But it’s not bloated.
The stated tuning profile takes inspiration from studio monitors paired with a subwoofer, and the sharp 150Hz bass shelf supports that. There’s also a gentle nudge around 400Hz that brings warmth to the lower midrange, pushing it closer to a more Meta tuning. Compared to the original’s woozier woofer, however, it’s more disciplined than indulgent. Up top and across the stage, the Hype 4 MKII sounds more separated and sorted than before, so even busy mixes stay tidy rather than slumped together.
The psychedelic flourishes of an album like Beck’s Sea Change float through with a kind of narcotic clarity, all shimmer, sigh, and negative space. There is, admittedly, some heat on top, a little treble flare, but that quicksilver snap contributes to a sense of speed and keeps haloed layers of phosphorescence detail neatly banked instead of throwing the whole balance off. This V-shaped incisive approach might be excessive for heavily compressed, high-octane genres except in moderation, but this heightened imaging is perfectly suited for more organically unfurling selections.
The Cypher takes the opposite approach, with a warm-neutral, mids-forward response that’s less about attention or extension and more about staying power. This is the kind of headphone you can listen to for hours because it would rather reveal than dazzle.
The Cypher’s bass is more planted than punishing, but it’s got grip for an open-back. It’s not thin and keeps low-end info intact, yet it’s defiantly uninterested in showing off. And the upper register has an anchoring, almost uncanny natural timbre, even if it’s not the most expansive. Treble is smooth, not spotlight-hungry, offering presence without glare. There are microdynamics, but they don’t chase spray-on sparkle so much as help coax pressure shifts from recordings.
Much like its closest spiritual cousins, the Sennheiser HD 600/650, rich, realistic vocal presence is the Cypher’s ultimate strength. But with more sub-bass staging. That same Beck album goes from prismatic reflection to lysergic confession. It’s laid out in a well-lit theater that’s wider than it is deep, spacious enough to sort every element’s honest intent but always kept to an intimate scale. If you’re monitoring for emotional weight, the Cypher lets it settle in your lap. Compared to the romantic voicing of similarly positioned Meze Audio headphones, the Cypher shows a mature restraint. The headphone is no longer demanding you constantly shift your attention; it’s keeping you company, handing you orange slices and telling you to relax.
The verdict
If the Hype 4 MKII is all velocity and contour, the Cypher is texture and tact. If the Hype 4 MKII reveals the foundation and framing of a track, the Cypher is the fixtures and fittings. Which is right for you comes down to whether you vibe more with a nervy display or deliberate composure. THIEAUDIO’s latest mid-fi one-two punch at $399 not only broadens the lineup, but it also clarifies the brand. One product says THIEAUDIO can still do spectacle; the other says it may finally know when not to.
