Fiio FA19 VS ThieAudio Monarch MK4

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Fiio FA19 brings a premium feel: a sturdy, slightly translucent shell with visible BA packs, comfy fit, and a plush eight-wire cable that terminates in 4.4mm. The MMCX sockets aren’t ideal, but the shell is vented, holds tips well, and the magnetic case feels upmarket. Sonically, this 10-BA set leans warm-neutral with a rich, cohesive presentation—male vocals sound full, some female vocals come off a bit husky, and bass has quantity more than tightness. There’s a touch of 5–6 kHz energy and slight hiss; treble is clean and pleasant rather than showy. The bass switch mostly bumps mid-bass; the lower setting keeps things tidier. Overall it’s Fiio’s most well-rounded tuning to date, just shy of “exceptional” because of that soft mid-bass and a mildly flabby midrange.

Versus peers, FD15 sounds more neutrally tuned (if less special), while all-BA options like Supernova feel more natural and controlled down low. In the wider field, sets like Letshuoer Mystic 8 (a bit of a sleeper), ThieAudio Monarch MK4 (cleaner upper-mids, dual bass settings), ZiiGaat Luna (tighter, crisper for far less money), or even budget-friendlier picks such as YU9 can offer a stronger value proposition. At around $1,000, FA19 earns a solid recommendation for those who enjoy a warmer, airy BA take—graded roughly A4 / S-—but it’s a demo-first purchase and shines much brighter if found used around $300–$400. Not a new benchmark, yet a very good Fiio with treble finesse and a smooth, easygoing signature that many will simply enjoy.

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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.