The Fiio FX17 emerges as a worthy flagship and a significant improvement over its predecessor, the FA19. This tribrid IEM boasts a unique driver configuration of one dynamic driver, four balanced armatures, and a staggering eight electrostatic drivers, all housed within a solid, lightweight titanium shell. While its aesthetic is considered a bit plain, the build quality is excellent. The package is loaded with a massive assortment of accessories, including seven different styles of ear tips and a cable with a clever built-in DAC adapter for smartphones.

Sonically, the FX17 delivers a warm, powerful, and engaging sound signature. Its bass is a particular standout, described as meaty, well-textured, and highly engaging without bleeding into the mids. The overall tonality is natural yet contrasty, offering a dynamic and punchy listen. The treble provides excitement and definition, though it can be slightly aggressive or "crashy" for those with high sensitivity, making it far from a "safe" tuning.

In direct comparisons, the FX17 is deemed superior in every way to the FA19, which was criticized for its bloated bass and splashy treble. It trades blows with competitors like the Dunu Glacier and ThieAudio Monarch Mk IV, offering a denser, more tactile experience than the Monarch's airy presentation and a more natural vocal tonality than the Glacier's more exaggerated V-shape. Ultimately, the FX17 is declared not only Fiio's best IEM to date but a compelling and engaging option in the high-end market.

The FiiO FX17 packs a hybrid 13-driver configuration featuring one dynamic driver, four balanced armatures, and eight EST drivers, priced around $1,500. Unboxing reveals a generous accessory suite: a premium leather case with magnetic closure, an MMCX removal tool, cleaning brush, cleaning cloth, and a magnetic cable holder. The highlight is the included modular cable with 3.5mm and 4.4mm terminations plus a specialized USB-C dongle enabling parametric EQ and firmware updates. Buyers also receive a staggering 22 pairs of ear tips – including SpinFits, liquid silicone, foam, bass-enhancing, vocal-focused, balanced, and double-flanged options – neatly organized across two cases. The cable itself earns praise for being soft, tangle-free, well-behaved, and featuring a functional chin slider.

Built from chunky titanium shells, the FX17 feels premium but substantial. While weight distribution prevents ear fatigue for some, its large size may cause fit issues for those with smaller ears, making a demo advisable. The nozzle diameter is 6.1mm. Sonically, the FX17 delivers a powerful, mid-bass focused slam described as punchy and meaty, though sub-bass rumble takes a backseat. The mid-range is warm, lush, and slightly relaxed, offering surprising clarity and excellent detail retrieval without shoutiness. Treble stands out as smooth, highly detailed, and non-fatiguing, providing ample air and shimmer without sibilance. Technical performance is strong, with great detail and separation, but the true star is the exceptionally wide, immersive, and realistic soundstage, particularly noticeable in the upper mids and treble.

Compared to the FiiO FA19, the FX17 offers a significant upgrade in bass physicality, smoother treble refinement, and superior soundstage. It also surpasses the Unique Melody MEST MKIII CF in detail, separation, stage width, and bass weight/texture. Against the pricier Elysian Apostle, the FX17 is warmer and more relaxed; the Apostle boasts tighter bass, clearer vocals, and sparklier treble, while the FX17 counters with a wider stage. This IEM is strongly recommended for mid-bass lovers seeking physical slam, listeners desiring warm, lush, non-fatiguing mids with clarity, treble enthusiasts wanting detail without harshness, and soundstage aficionados. It's not ideal for those with small ears due to shell size, listeners prioritizing deep sub-bass rumble over mid-bass impact, or anyone seeking a neutral or bright tuning. The FX17 earns a four-star rating for its standout qualities.

The FiiO FX17 is a mind-bending flagship IEM priced at $1,500, packing an absolutely hilarious 13-driver configuration per side: one dynamic for bass, four balanced armatures for midrange control, and a staggering eight electrostatic drivers for the highs. The sheer number of electrostats isn't a gimmick; FiiO explicitly states they're necessary to achieve sufficient sound pressure and avoid being mere "decoration," throwing serious shade at competitors. The result is nothing short of wild. Forget typical soundstage descriptions – the music doesn't feel like it's coming from two points in your ears or even from speakers in a room. Instead, it creates an entirely internalized, coherent performance happening inside your head, like the band is set up within your skull. It’s a cognitive living experience prioritizing placement and realism over simple frequency response graphs.

This psychoacoustic magic translates into pure, infectious enjoyment. Tracks feel aggressively present yet controlled, with kick drums hitting the back of your eyewall and intricate details like tap dancing percussively located behind your eyes. The separation and realism are phenomenal, making everything from the Beastie Boys to complex techno feel immediate and utterly engaging. While physically large with a fingerprint-prone mirrored finish and using the less-favored MMCX connectors, the FX17 is surprisingly comfortable and not overly heavy. Criticisms like the connector type are dismissed as irrelevant noise compared to the sonic achievement. Plugged into anything from a high-end stack to the included USB-C dongle DAC, the FX17 delivers its unique, immersive magic consistently.

The unboxing experience screams flagship, absolutely justifying the price tag visually. It arrives in a luxurious British Racing Green case with magnetic closure, featuring gold-accented packaging, a wooden storage plaque (unit 240 shown), a cleaning cloth, MMCX tool, ear wax brush, magnetic cable clip, and a mind-boggling 22 pairs of various eartips. Add in a very nice cable with interchangeable terminations (3.5mm & 4.4mm included, 2.5mm adapter not included) and the aforementioned USB-C dongle, and the package feels comprehensive and premium. Ultimately, the FX17 stands out dramatically in the crowded $1,500 IEM field. It’s declared worth every penny of $2,000, delivering a unique, transformative listening experience that prioritizes how the sound is presented over traditional audiophile checkboxes. It earns full, emphatic marks as FiiO's best audio reproduction product to date.

The ThieAudio Monarch MK4 is a premium IEM that earns a spot in the S-tier for competitive gaming, offering a significant upgrade over its predecessor and A-tier competitors. It features a unique rumble mode switch that adds a satisfying low-end punch and weight without muddying the detailed, reference-grade tuning of the standard mode. While the CNC aluminum build feels exceptional, the design is a bit bulky and heavy, which can lead to some comfort issues during very long, multi-hour sessions.

For gaming, the technical performance is nothing short of phenomenal. The imaging is holographic and the depth perception is absolutely exceptional, providing a critical advantage in tactical shooters like VALORANT where tracking footsteps through walls becomes incredibly precise. The wide and deep soundstage pushes sounds off the player, creating an immersive experience. While rumble mode is preferred for titles like Call of Duty, the standard mode's clean and detailed signature shines in battle royales like Apex Legends, though the 2-4k range can make gunfire a bit shouty at higher volumes.

This is also an absolutely amazing set for music, delivering an elevated level of technicality and resolution. The standard mode offers a fast, clean, and neutral listen with great detail retrieval, while the rumble mode provides a weightier, more engaging bass profile for tracks that benefit from the extra warmth and punch. Ultimately, it's a very high-end IEM that delivers a top-tier experience for both competitive gaming and critical music listening.

ThieAudio Monarch MK4 comes in at $1,150 with a tribrid array—2 DD + 6 BA + 2 EST—a chunky stock cable with friction-fit swappable terminations, and a genuinely excellent, in-ear-operable “Rumble” bass switch. The new metal shells look tidy, but the fit is very large; on average ears it tends to sit a bit out of the concha and feel unstable (seal is doable, comfort is mediocre). Build details like the firm chin slider are nice, yet the cable bulk and loose termination retention detract from daily use.

Tonally, stock MK4 aims for a clean-neutral presentation with a meaty, sub-bass-focused lift, lively upper registers, and excellent extension. The flip side is a slightly dry / clinical character with a hint of treble hardness that can leave notes feeling a bit bodyless. Engaging Rumble mode thickens the curve from ~300 Hz down—more warmth and weight, bordering on “gigabass” territory—making the set fuller and more fun, though arguably too bassy for purists. Staging and imaging are solid, and resolution is high, but macro-dynamics land behind peers; compared side-by-side, sets like Dunu Glacier and 64 Audio U4S feel punchier, while Valhalla sounds warmer, smoother, and more effortlessly resolving.

Overall, MK4 is a technically capable tribrid with two distinct tunings on tap—clinical-clean stock and warmed-up Rumble—but it’s held back by fit size, cable quirks, and that slightly wooden bass texture. For listeners chasing a bright-leaning neutral with legit sub-bass reach (and who can accommodate a big shell), it’s a compelling try; in this lineup, though, it settles at a three-star recommendation next to more engaging or comfortable alternatives.

Priced between $1,150 and $1,300 depending on custom faceplate options like the butterfly design shown, the Thieaudio Monarch MK IV boasts exceptional build quality with a large but well-contoured titanium shell offering a secure and comfortable fit. Key features include the innovative rumble switch for adjustable bass levels on the fly, a durable two-pin connector, and a solid feel that inspires confidence in longevity. While the included accessories are considered fair but unexciting, the shell's customization potential and rugged construction are major highlights.

Sonically, the Monarch MK IV delivers a detailed, exciting, and clean sound signature that stands as the best in the Monarch lineage. The rumble switch provides two distinct profiles: the red switch (no rumble) offers a balanced, tactful bass presentation, while the gold switch (rumble) adds a satisfying sub-bass shelf ideal for genres like hip-hop. Treble performance is notably improved over the MK III, though a 10k peak requires careful ear tip selection for some listeners. It trades blows with flagships like the $3,000 Annihilator (better sub-bass focus) and the $1,800 Elysian Apostle (more vocal forward), often matching or exceeding their technicalities while offering its unique tuning flexibility.

Scoring a top-tier 9.8, the Monarch MK IV earns its place through a compelling combination of premium build, the highly functional rumble switch, and outstanding sound quality that feels both special and refined. While acknowledging the high price, it represents significant value against competitors like the $2,000 Thieaudio Valhalla or the fiddly Grand Maestro, offering a feature-rich, durable, and sonically excellent package that justifies its position as a current summit-fi favorite.

The Thieaudio Monarch MK IV presents two distinct tuning options, elevating its versatility. The balanced switch delivers a clean, smooth, and slightly airy presentation, offering a refined all-rounder sound that's very detailed, well-layered, and resolving – essentially a direct upgrade to predecessors like the Monarch MK3 and Top Pro, with slightly more treble detail and air. Conversely, the bass switch provides a significantly fuller, warmer low end with punchy, well-textured bass and a tamer upper midrange, addressing criticisms of thinness in earlier models and offering a specialized, engaging listen for bass-heavy genres.

Technically, the MK IV sits comfortably in the $1,000 tier, offering a slight bump in detail retrieval, refinement, and smoothness over the MK3 and MK2, comparable to the Dunu Glacier and Prestige LTD. While not a giant leap, the dual tuning options make it arguably a better all-rounder than single-tuning competitors; the balance switch excels with acoustic, classical, and cleaner genres, while the bass switch shines with rock, metal, R&B, and pop. Build quality is improved with an all-metal shell, though the flimsy cardboard case is a notable disappointment. Vocals are smooth, balanced, and enjoyable, though sets like the Monarch MK2, Mystic 8, RSV, or Arcanis offer more forwardness or unique character. Bass quality is excellent for most, though pure bass enthusiasts might prefer models like the Thieaudio Origin for its unique texture.

Ultimately, the Monarch MK IV is a highly compelling endgame option for the vast majority. It combines strong technical performance with exceptional versatility through its two excellent tunings, covering a wide genre spectrum effectively. While value-focused options like the Top Pro, Volare, or Mega5EST offer similar technicalities at lower prices, the MK IV's refinement, tuning flexibility, and slightly superior performance make it easy to recommend. It allows listeners to leave the hobby satisfied, provided they resonate with its sound – though chasing marginally better flagships involves steep diminishing returns. The king might be debatable, but the MK IV is undoubtedly a very solid $1,000 contender.