KURO, like all Flat4 earphones, is a dangler. It’s two massive, Frankenstein bolts that plug, rather than nestle, into your ears. One sidewise fall and it’s lights out. Some intrepid, elf-eared types will be able to wear it with the cable going north, over the ear, but most people will find that hanging the cable down is the best way to wear KURO. There still is no neck cinch to keep the earphone cable from flopping around and transferring subtle nipple noise up to your ears.
Despite having made crazy speakers and headphones in the past, Mr. Yamagishi has a good sense of style. At the centre of his business is tea. You can’t get any less kitschy than tea. KURO’s tea tin carrying case, supple practical cable, and legible fonts lend themselves positively to Ocharaku’s image. It’s a return to true Japanese aesthetic, not the terrible jerrybuilt after war designs that hold sway from Toyota to basically everything at the grocery store.
Considering KURO’s open nature – not to mention the fact that it comes packed in a tea tin – it’s fair to say that it isn’t an active-use earphone. Footsteps and purposeful swats will elicit small, low-pitched thumps to the ear, but overall, touch noise is minimal. The cable is anchored firmly into KURO’s body and a thick rubber nub protects it from cleavage. That’s the good stuff.
Somewhat poor stress reliefs are plugged into the y split and 3,5mm jack. But they are no worse than any Flat4 earphone.
As a family, Flat4 has a very similar sound: full bass, tight mids, spacious soundstage, and somewhat strident highs. KAEDE and KURO are the crowning achievements in this series.
KURO follows KAEDE’s footsteps, providing clear mids and, generally, smooth transitions from upper mids to highs. KURO throws impressively wide instrument splays and central, well-grounded bass. It is never anything but crisp.
KURO’s stereo width and out-of-head performance aren’t typical of in-ear earphones. The sound they produce is reminiscent of large, open-backed headphones. Of particular note is the vocal band. It’s clear and forward. Cymbals shimmer in at the sides and fade away to blackness; bass rumbles up from below, in a chamber all its own. Rhythm guitar, piano, and violin vibrate at the sides. Despite each element being infundibulated into the same canal through a narrow, plastic tube, the sound is very open and organic.
Generally, KURO keeps up with all genres of music. Even the hard edges of speed trance and thrash metal retain crispness. Cymbals shimmer doesn’t hang on too long and drums attack in quick strikes, then let up. And drums are amazing.
Bass vs. Mids
KURO’s mids, while sweet, err to a sense of space and clarity rather than sappy acoustics. Bass, with its slightly higher sound pressure, is forefront in comparison- not in a thumpy way, though. Bass is über detailed and boasts the single most sonorous resonance that I’ve heard in an IEM to date.
Bass vs. Highs
Both bands are energetic. KURO is less fatiguing than SUI is, but it isn’t an all-day, easy listening earphone. Listeners who favour earphones with strong treble presentation will fall in quickly with KURO. Newcomers may need time to acclimatise their ears. The contrast between bass and treble isn’t stark, and mids don’t get pushed down. Because of the amount of detail KURO’s bass offers up, duff-bassheads may find KURO to neither nor there. The presentation is audiophile first, big second.