Most obviously, the housings for the earcups have been upgraded to a genuine black walnut wood with a matte surface, an attractive look compared to the drab all-black TH-600 cosmetics. The TH-610 design also features updated large 50mm drivers measuring a potent 1 Tesla (1,000 Gauss) at the magnetic circuit for maximum dynamic extension.
Per manufacturer specs, the proprietary Fostex ’Bio-Dyna’ transducers output an extremely wide frequency range rating down a jaw-rattling 5 hZ in the lows all the way up to 35,000 kHz in the uppermost highs. A 3-meter detachable headphone cable constructed of 99999.99% pure copper-free oxygen (OFC) braid identical to the one on the flagship TH-900 MKII model comes with the TH-610 and replaceable synthetic leather angled earpads are also standard.
In our Headphone.com review opinion, the Fostex TH-610 clearly punches above its fighting weight and even approaches the performance of some headphones at twice its price.
In particular, the balanced unity of the sound from top to bottom is remarkably coherent with each instrument remaining distinct and full-bodied in the overall presentation. Voices sound chesty and well-meshed into the production and rarely exhibited recess, instead sounding pleasantly human and emotional with a wide array of music and studio recording styles. Bass heft and texture is also better than the old TH-600 with a brawny fullness evident in the TH-610’s lowest register that carries a solid foundational weight along with audibly improved texture.
The soundstage imaging is remarkably spatial in the Fostex TH-610 with good layering and instrumental proportion noted even on tightly congested recordings. On the rare original Tablighi Records LP of Abdul Rahim Ibrahim’s 1977 spiritual jazz-funk masterwork, “Al Rahman! Cry Of The Floridian Tropic Son,” the oceanic layers of off-kilter acoustic guitar, electric piano, chanted vocals and funky African percussion are crisp and forcefully delineated in the TH-610 despite the murky pastel wash of the production.
On the down side, the Fostex TH-610’s transient attack is not the fastest we’ve heard so it falls behind the dynamic speed and quickness of the bellwether Fostex TH-900 Mk II headphone.
Compared to the exceptionally liquid tone of that top can, the TH-610 comes up more dry with a bit less meat on the bones of the music and less lush tone. The Fostex TH-900 has an engaging albeit famously colored tone that tends to add some shimmer and sparkle. In contrast, the TH-610 seems to have a less aggrandized sound that still delivers great resolution, but with less presence and intensity.
As with many of the full-size circumaural Fostex headphones, the TH-610 fit is geared for slightly bigger heads with a light headband clamping force that is nicely gentle on the head. However, smaller-noggin folks may suffer from the pesky headband slippage issues common to the bigger Fostex cans.
Good ambient isolation is still there thanks to the soft ergonomically angled earpads which completely cover the earlobes. The seal won’t completely shut out the world but it will help keep your music from leaking out and potentially disturbing others nearby, meaning the Fostex TH-610 can be used in close quarters with good listening privacy and isolation.