Наушники — Fosi Audio i5

Fosi Audio released the open-back i5 as its first headphone of any kind. The company began in 2017 with amplifiers and later added speakers. It was launched through a Kickstarter campaign in spring 2025 before moving to regular sale, and Fosi lists it at USD 589.99.

Key specs that matter

Fosi fits each side with a 97 mm planar driver whose diaphragm is 2 microns thick, with a 1.3 micron silver coating applied by magnetron sputtering. The magnetic system uses 22 N50 neodymium magnets per driver, arranged symmetrically on both sides of the diaphragm. Nominal impedance is 28 ohm and sensitivity is 98 dB per mW at 1 kHz. Fosi quotes a frequency response of 10 Hz to 50 kHz, THD below 1% at 100 dB SPL and a maximum level of at least 120 dB SPL. The recommended amplifier power is 500 mW or more. The headphone weighs about 550 g.

Engineering and use context

The earcup chambers are made of walnut wood set into a CNC-milled aluminium frame. A memory-steel headband keeps its shape while staying flexible, and a sheepskin suede strap rests on the head, with a stepless friction slider for size. The cups rotate on two axes to adjust to different head shapes. A rigid, open acoustic mesh placed ahead of each driver damps air pressure. Earpads combine perforated leather with a breathable fabric face over memory foam. A removable lead connects to standard 3.5 mm sockets on both cups, so 3.5 mm and 4.4 mm aftermarket leads fit. In addition, the box contains a 3.5 mm cable with a 6.35 mm adapter, a user manual and a carrying case, with a balanced 4.4 mm cable offered in some packages. The stock wire uses 1,120 strands of silver-plated 5N OFC copper, while an upgrade lead with 48 strands of CVD graphene copper core is sold separately. Kickstarter backers paid USD 387, or USD 439 with balanced cables. The open-back design leaks sound into the room and lets outside noise in, so the i5 is aimed at quiet home listening. Fosi gives a two-year warranty and a 30-day money-back period.

Pairing

The recommended drive level points towards a desktop headphone amplifier rather than a phone output. Fosi's K7 DAC and headphone amplifier has a balanced output with ample power for the i5 when used with the balanced cable, and its single-ended output also works with the supplied lead.

Alternatives

Fosi Audio makes no other over-ear headphone, since the i5 is the brand's first and only model of this type.