KZ Castor Pro (Harman Target with Improved Bass)

A bass-forward, V-leaning take on the Harman idea rather than a neutral one: generous low end, a presence peak at target level, a relaxed upper-midrange and some sparkle on top. Reviewers who like it call it energetic and fun; critics call the balance odd or muddy. Sources agree this version is not for anyone after neutral — and that the switches, which mostly move the bass, give real room to adjust.

“力強い低音 刺さりすぎない高音 エネルギッシュな強ドンシャリサウンド”

翠煙, note.com (Japanese: 'powerful bass, treble that doesn't pierce too much — an energetic, strongly V-shaped sound')

“It is essentially a modified bassy V-shape sound.”

bluranerd, Head-Fi

“the improved bass version may not suit listeners looking for a more neutral presentation.”

Muhammad Fahad, GeekHunk

“Highly tunable sound with effective switches”

RedditRecs (aggregated from 239 Reddit reviews)

Sources split three ways, and the split is about quantity in both directions. Most — editors, video reviewers and the bulk of owners — hear a powerful, punchy, satisfying low end. A critical minority hears too much of the wrong kind: a mid-bass hump that bloats and muddies the lower mids. And a smaller group of buyers finds it lighter than the 'Improved Bass' name promised. The measurements back the first two readings at once — the lift is heavy around 100 Hz but close to target in the deepest sub-bass — while the third tracks tip seal and expectations set by bass-boosted wireless earbuds.

Sources split: a minority hears a surprisingly clean, clear midrange (male vocals especially) that survives the bass, while more hear mids that are recessed, thin or muddied — pushed back by the bass below and a scooped upper-midrange above. The measured dip at 4–6 kHz and the mid-bass lift carrying into the lower mids explain both 'thin' and 'muddy'.

Sources split, and critics lean one way: most detailed reviews hear a treble that turns sharp, shouty or sibilant — especially at high volume, on bright tracks or for treble-sensitive ears — while a smaller camp, mostly owners, hears it as energetic and airy without piercing. The switches don't change it (they move the bass), so a set that bothers you in one setting will in all of them; EQ or tips are the fix owners mention.

A recurring pleasant surprise: most sources hear a wide, open stage for the price — more open than the original Castor — and one video reviewer finds it deeper than it is wide. The lone dissent comes from a critic who hears the bass costing it space, as it does detail.

“Wide soundstage and excellent imaging for gaming”

RedditRecs (aggregated from 239 Reddit reviews)

“The pro's also offer a much more open and natural sound stage”

Solid_Steam, r/iems

“Alongside this is an actually decent sense of space and imaging.”

bluranerd, Head-Fi

Sources split, mostly over gaming. Most hear sharp imaging and separation that is good for the price — enough to place footsteps in CS2 for some owners. Others find the bass masks directional cues in competitive shooters, and RedditRecs lists 'subpar for competitive gaming' among its top cons. For music and single-player games it's a strength; for ranked FPS, the brighter Harman version or a leaner set is the safer pick.

Good for the money, by most accounts — two reviewers call its technical performance excellent or top of its class at the price. The dissent is about the bass getting in the way: one critic calls the fidelity average, and an owner coming from the original Castor heard a drop in overall quality.

“the technicalities are excellent”

Always In My Ears (YouTube)

“High-quality and detailed sound”

RedditRecs (aggregated from 239 Reddit reviews)

“I find them to be average across the board because there's a lot of bass, but the quality and fidelity doesn't come across as clean or anything special”

LesModio (YouTube)

Easy to drive and composed at volume: a phone or a basic dongle gets it plenty loud, and reviewers note it holds together at high volume without the crackle cheap sets can show. One video reviewer hears the treble start to overtake the mids near maximum volume.

“The earphones also remain stable at high volume.”

Muhammad Fahad, GeekHunk

“there's no like realistic use to use a dedicated dongle DAC amp to get the most out of this set”

LesModio (YouTube)

Sources split, and the physical cause is clear: the shell is large and heavy for a budget IEM, with a long, thick nozzle that goes in deep. A majority of sources — critics, owners on Reddit and RedditRecs' top con — find it bulky, tiring or painful over time, especially with smaller ears. Others, including one of the critics, find it comfortable once they find tips that suit them; the stiff stock ear hooks and tips add to the complaints.

Sources split along a reviewer-versus-owner line. Reviewers like the metal-faceplate, resin-shell build, and some call it premium for the money. Owners' reviews add a durability record: a dead or weakened channel within weeks or months, a loose socket, driver flex, a faulty cable — reported in Amazon's critical tail and a small share of Headphone Zone's owner reviews. The stock cable (stiff, with awkward ear hooks) and tips draw complaints from critics, several of whom recommend replacing both.

Rarely discussed. The deep-seating nozzle gives a useful passive seal once the tips fit — and, like the bass, it depends on that seal.

“Once inserted correctly, they also provide a useful level of passive noise isolation.”

Muhammad Fahad, GeekHunk

Sources split, and price is the hinge. Owners and most reviewers call it a budget king — tunable, bassy and well-featured for very little money, especially on the frequent sales. Critics are cooler: at its ~$25 list price one grades it a D+ and says it isn't worth it, another would only recommend it on deep discount, and an owner in a 'regret' thread liked it only until they heard other sets.