ThieAudio Hype 4 MKII Review

Today, we review the ThieAudio Hype 4 MKII IEMs. It is selling for $399 USD.

Disclaimer: Linsoul gracefully provided the ThieAudio Hype 4 MKII. Just like always, this review reflects my unbiased perspective and honest experience with the product.

ThieAudio

Launched in 2019, ThieAudio specializes in the R&D of audiophile in-ear monitors and headphones. I have always seen ThieAudio as a safe harbor in the sea of Chi-Fi. This may sound hyperbolic, but I believe it accurately reflects the brand. There are many companies in this industry, and many of them release good products from time to time, but ThieAudio has reinforced its position release after release with an impressive hit rate.

The Monarch MKII was the specific model that put them on the map. Since then, ThieAudio managed to keep that momentum going with successful releases like the Oracle MKII, Prestige LTD, Valhalla, and, most recently, the Monarch MKIV.

Today, we are focusing on the Hype 4 MKII, the first second-generation model in the Hype series. Following a fairly long wait, it retains its position as the mid-range option in the current lineup. More importantly, it feels like a mini Monarch MKIV in several meaningful ways, which I will explain throughout this review.

ThieAudio Hype 4 MkII

The Hype 4 MKII is a 2DD + 4BA hybrid built around the second-generation IMPACT² subwoofer system, the same implementation found in the Monarch MKIV. It sits at $399, unchanged from the original despite the gap of nearly two years and the tariff turbulence the industry has navigated in between.

The original Hype 4 was a warm-neutral all-rounder that earned its reputation on tonal balance and bass control. The MKII is different on first listen, more agile, more technical, more transparent, with a clear lineage to the current flagship. The MKII is a complete ground-up redesign rather than a tweak or a retune, and the engineering brief seems to have been written around the same formula as the Monarch MKIV.

To my ears, it is basically a mini Monarch MKIV. Compared to the OG Hype 4, the new gen feels like a genuine generational leap in SQ, to my ears. Whether this direction works for you will depend on your taste and expectations. I hope to answer some of your questions with this article.

What’s New?

Almost everything is new. The MKII is a ground-up redesign rather than a retune and repack. There is a lot of ground to cover, so let’s go.

First and foremost, the IMPACT² subwoofer has leveled up and moved to its second generation. ThieAudio dropped the dual 10mm dynamic drivers of the original and replaced them with dual 8mm composite diaphragm units in a new pneumatic acoustic chamber.

The crossover cutoff has also been pulled in from around 200Hz to 150Hz with a sharper slope. It’s the exact same setup we’ve seen on the mighty Monarch MKIV, and that’s awesome.

The balanced armature config has been fully changed. The Sonion drivers of the original are gone, replaced by a Knowles-only setup: two RAB series drivers for the low-mids, an ED-33465 for the mid-treble, and a RAD-33518 tweeter sitting in the nozzle for the top end. The crossover has been redesigned around this new array, moving from three-way to four-way.

The shell is no longer medical-grade resin. Actually, shell is no longer acrylic at all. ThieAudio has switched to CNC-machined aluminum shells with anodized finish. The faceplate is a cracked mosaic that shifts between green, teal, purple, and everything in between.

The cable has been FINALLY upgraded! The fixed 3.5mm silver-plated OCC cable of the original has been replaced by a thicker 6N monocrystalline copper design with a modular plug system, including both 3.5mm and 4.4mm terminations in the box.

Packaging & Accessories

This is the first time in roughly five years that ThieAudio has updated its packaging, and the change is overdue. Up to this point, almost every model in the lineup, from the Hype 2 all the way through the Monarch and Oracle series, arrived in the same cardboard box with minor variations on the sleeve artwork. The Hype 4 MKII finally breaks that pattern.

The new box is compact and rectangular with a sliding outer sleeve, printed with the Hype 4 MKII artwork, the driver configuration, and the usual marketing mumbo-jumbo. Underneath the sleeve sits the nicely designed inner blue box that opens upward and flips over, revealing two flaps. The left flap covers the accessories compartment, and the right flap holds the carrying case and the IEMs themselves seated in dense foam cutouts. The whole presentation feels premium and well-designed.

The carrying case is also new, and it is one of the more premium cases I have seen included with an IEM at this price. It is a grey leather zippered case with ThieAudio branding etched on top. It offers a good balance between protection and practicality, with a size that comfortably fits the IEMs and a medium-sized dongle like the iBasso DC-Elite or the A&K HC5. This is the kind of case I can actually use daily, which is surprisingly rare because of all the bulky cases popping up.

The cable is new, too, and is a huge improvement over the generic-looking brown cable that came with the original Hype 4. This time, the Y-split, 2-pin housings, and other elements are of much better quality.

The MKII ships with a thicker 4-core 2-braid 6N monocrystalline copper cable in an ocean-blue transparent jacket, with the interwoven inner conductors visible through the sleeve. It finally features a modular plug system and comes with both 3.5mm single-ended and 4.4mm balanced plugs. The cable is surprisingly supple.

Ear tips have always been where ThieAudio fell short, and this didn’t change. The Hype 4 MKII comes with two sets, silicone and memory foam, each in S, M, and L. The selection is just OK, though tip rolling will likely still happen for most listeners. Apart from these, you get four adhesive wax mesh replacements, a warranty card, and a wearing diagram.

The overall presentation feels more premium with the new packaging overhaul. It’s definitely a step in the right direction. The cable and carrying case are a huge improvement over the OG Hype 4. ThieAudio has clearly put a lot of thought and care into the unboxing experience for their latest generation of in-ear monitors. Well, it was time.

Design & Build Quality

The leap in build quality compared to the original is impossible to overstate. ThieAudio has moved away from the acrylic resin used for the Hype series, switching to CNC-machined T6 aluminum. This makes the MKII only the third IEM in the entire range to have a metal shell, after the Valhalla and Monarch MKIV. The shells are milled from solid aluminum blocks, hand-finished, and anodized to give them a matte black finish that looks exquisite in person.

The difference is huge in hand. The shells feel dense and cool to the touch, and look like they could survive a nuclear explosion. The aluminum chassis is assembled from three components: one part that incorporates the front panel and the 2-pin connector; one part that extends to the nozzle; and the nozzle itself. The joints in between look flawless; I didn’t notice any misalignment or assembly issues.

According to ThieAudio, each unit is hand-assembled and undergoes independent rounds of quality inspection at every stage, from individual driver pairing and assembly to shell processing, final assembly, and packaging. The unit I have in hand is flawless, and that has been my experience with their products since 2020.

The first thing that catches your eye is the faceplate. It features a shattered mosaic inlay with an iridescent finish. Although the surface lacks physical depth, the cracks between the tiles create the realistic illusion of depth. The valleys are finished in a textured, rough, matte black material that contrasts well with the iridescence. I’m really impressed by the level of fine detail.

The inlay is highly light-reactive, shifting through shades of purple, green, teal, cyan, and ultramarine depending on the angle. It is one of the best faceplates I have seen for under $1k. Having been involved in this hobby for over 15 years, I can confidently say that these are some of the best-built IEMs I have ever owned.

They have also considered the functional details. The wax guards are replaceable, and ThieAudio includes four spare guards with pre-applied adhesive, a thoughtful inclusion that I wish more brands would pay attention to. There is a three-dot vent on the upper-forward face of each shell to handle pressure normalization for both the driver chamber and the ear canal during insertion.

Sound Impressions

Sound Signature

For this review, I tested the Hype 4 mkII with the Chord Hugo 2, Topping DX9 Discrete, and Astell&Kern HC5. The Hype 4 MKII is not difficult to drive, but it does scale nicely with cleaner and more resolving sources.

The Hugo 2, as usual, gave me the clearest picture of its capability and performance, while the DX9 Discrete highlighted tonality and low-end control. The HC5 was also a good portable pairing, especially if you want to keep the presentation slightly smoother and more relaxed up top.

The Hype 4 MKII is a neutral IEM with a pretty sweet sub-bass boost. It’s a U-shaped monitor with a highly transparent nature. It has an elevated sub-bass, a balanced mid-bass, a clean and linear midrange, lively upper mids and lower treble, and an expansive upper-treble.

It is not a thick, warm, romantic, or vocal-first IEM. It is more agile, open, precise, and energetic, with plenty of bass authority to keep things fun and engaging. It is a tuning that prioritizes clarity and separation across the spectrum without sacrificing the fun factor.

I call it the mini Monarch MKIV, or ”budget-conscious man’s monarch ” mainly because, to my ears, this is the closest ThieAudio has come to the golden line-up of Monarchs. The Hype 4 MKII does not just borrow the Gen 2 IMPACT² hardware from the flagship; it also shares its tuning philosophy, in my opinion. There is a clear common DNA in how the two sets handle agility, dynamism, and the balance between technical precision and musical fun. The MKIV is more refined, more resolving, and more flagship in every measurable sense, but the MKII captures the essential character at a much lower price, and that is genuinely impressive.

What impressed me most was how technically capable it feels for $399 USD. The Hype 4 MKII has excellent separation, fast and punchy bass, strong PRaT, pinpoint imaging, wide staging, and very good detail retrieval. It does not sound like a typical $400 hybrid to me. In terms of agility, clarity, and overall technical performance, I think it pushes closer to the $600-700 range, which is why I find its value proposition so strong.

The overall character is fun but not loose, technical but not analytical, energetic but not disjointed. That balance is difficult to pull off. Many IEMs in this price range either chase warmth and body at the expense of resolution, or chase clarity and end up sounding thin or fatiguing. The Hype 4 MKII is not one of those, though; it seems to have found a happy medium.

Bass

The original Hype 4 was a bass-forward IEM by design. It carried substantial bass quantity through the IMPACT² isobaric system and leaned into a quantitatively heavier low end overall, setting the tonal foundation for everything above it.

Luckily, the mkII’s sub-bass impact remains excellent and just as authoritative. The Hype 4 MKII still hits hard where it needs to, and the elevation is roughly comparable to the original in raw quantity. Where the MKII pulls ahead is in speed and recovery.

The bass on the original was satisfying but relatively relaxed in its decay/recuperation, while the MKII is MUCH faster and more agile. That single change cleans up everything that follows and gives the bass a sense of precision that the OG simply did not have. This is a meaningfully better quality of bass, and the lineage to the Monarch MKIV is obvious in how it handles complex tracks with congestion-prone twin pedal passages.

The mid-bass is the first major change. ThieAudio has pulled back the mid-bass region and tightened the cutoff, which means the MKII has noticeably less mid-bass warmth than the original. The OG Hype 4 used that mid-bass shelf to add body and richness to the lower midrange, while the MKII trades that warmth for a cleaner separation between bass and mids.

The result is a low end that feels faster, leaner, and more focused, with no bleed and no thickness clouding the lower midrange. Some listeners who specifically loved the warmth of the original will notice the absence, but in exchange, you get a low end that prioritizes texture, control, and rhythmic agility over body. Plus, you get the U-shape bonuses, such as the improved stage depth, width, and overall sense of improved spaciousness.

Midrange

The original Hype 4 had a clear, slightly warm midrange with a natural timbre and slightly forward vocals, sitting in a comfortable, warm-neutral zone that worked well across genres.

Vocals on the MKII sit slightly further back than on the original. This is not a recession in the dipped-vocal sense, and the coherence between the lower and upper midrange is preserved cleanly, but the vocal plane has been pulled back enough to create more contrast between the vocal and the instruments scattered around within the stage. The change might seem negligible on paper, but the impact on the overall presentation is significant.

Soundstage width opens up considerably, depth improves, and imaging becomes noticeably more precise. The MKII has clearly superior staging and imaging compared to the original, and this midrange adjustment is one of the main reasons why.

Timbre is excellent. Strings have correct bite, acoustic guitars have natural decay, piano keys are reproduced with the right body, and the lower midrange has enough density to keep instruments grounded despite the leaner mid-bass behind it.

The reduction in mid-bass warmth makes the midrange sound cleaner and more transparent than the OG, with better separation between layered elements.

In my opinion, this is a more grown-up midrange tuning, and it pairs naturally with the more technical character of the new bass and treble.

Treble

The ear gain region is tuned almost identically to the original Hype 4, so the fundamental upper midrange character carries over. The differences begin to emerge past that. Lower treble on the MKII is slightly more energetic than on the Hype 4 OG, which is the primary reason detail retrieval feels noticeably elevated. Fine detail can be tracked more easily, high notes are cleaner, and the overall sense of resolution is a clear step above what the original delivered, without sibilance or excess shoutiness.

The OG Hype 4 had a more diffused and restrained upper treble presentation, with energy spread across a broader range. The MKII concentrates its upper treble peak around 15kHz. This tuning choice strengthens the sense of air and spaciousness without introducing any harshness in the lower treble, and it gives the top end a level of openness and extension that genuinely feels similar to what the Monarch MKIV does in that exact spot.

As with any IEM that has an upper-high peak, this is worth flagging for treble-sensitive listeners: the MKII can come across as bright. At normal listening volumes, that brightness comes across as addictive and detailed, with the kind of hi-fi sparkle that makes acoustic guitars sound vivid and alive. Push the volume higher, around 95dB SPL and above, and the same peak can be fatiguing on poorly mastered tracks.

The review continues on the next page. Click here or use the jump below.