Since I was vacationing in Shenzhen, I paid a visit Fosi Audio office, self-collected the i5, and saved them the trouble of shipping the headphones to me.
The Fosi Audio i5 comes in a massive box with a magnetic flap cover. Thick sponge protects the headphones from rough shipment. Included in my pre-launch review unit are 3.5mm and 4.4mm cables of 1.8m length in a cloth bag, as well as a 6.35mm adapter. The pre-order version in Kickstarter will include an additional 4.4mm upgraded cable and extra pair of earpads depending on the bundle.
At 550 grams, the headphones are rather heavy and slightly tight, but the weight and pressure is alleviated with the suede leather headband. The earpads are thick, using fabric on the sides in contact with the head, and perforated leather on the outer areas. I totally love fabric earcups as they are more breathable and lasts longer, though I would last longer if they are lighter.
Encasing the 97mm planar magnetic drivers is the aluminium frame encircled with walnut wood finishing. The ear cups practically tilt and swivel in all directions without restrictions. The overall design is pretty much similar inspired by headphones like Hifiman, but Fosi Audio manages to distinguish their creation starkly with the S-shaped grille accent.
On specs, the i5 headphones produces more than 120 dB SPL, with 10 – 50,000 Hz frequency response. With 28-ohm impedance and 98dB/mW sensitivity, Fosi Audio recommends more than 500mW of power to listen to them. They drive quite well on normal devices and I don’t need to turn the volume too much, but you definitely get better performance with more premium amps.
Audio Experience
I feel that as a first pair of headphones designed by Fosi Audio, they have aimed to deliver a sound signature that takes the full advantage of the planar magnetic driver characteristics while tuning to achieve the sonic features of dynamic drivers.
Without the need to turn up the volume too much, I still manage to hear snappier sound, more obvious nuances, more refined percussions. But unlike other headphones, the details are not the result of just making the details louder. The i5 just makes the instruments less veiled. Having a massive driver size of 97mm means the sound is delivered over a larger plane so the music is not cluttered. The sound staging is not too wide and while they sound close enough to let me hear details, they are not too in-your-face.
To my ears, the i5 does not sound excessively bright, because it expertly balances the treble sparkles with the bass and midrange warmth. The low frequencies have sufficient resonance to achieve depth, punchy impact yet they do not linger too long to obstruct the musical presentation. The i5 also delivers more midrange details from instruments like Rhodes piano without the bloom, adding more joy to my easter-egg hunt for new sounds.
The i5 is tuned such a way to avoid sounding harsh to the ears, particularly the upper midrange. It also brings the bass more prominence, the midrange sounds full and clean, while vocals do not stand out in the mix, saxophone and trumpet solos sound warmer and less uncomfortable at loud volumes. Yet, they are not dark-sounding, nor does the treble roll-off. If you pick tracks without much bass, then the i5 can sound quite transparent.
I like that the i5 lets me listen comfortably to albums with heavy and harsh treble mixes like Ayumi Hamasaki. I like that the i5 makes jazz albums like Tsuyoshi Yamamoto Trio’s “A Shade Of Blue” sound more “live” as the headphones bring out the unintended recordings of the performers’ voices and cues. Basically, for albums that sound harsh due to excessive upper midrange peak, I can listen to them at louder volumes and enjoy the overall music arrangements and recordings.
For my review, I paired the i5 with the
Creative Sound Blaster X5 running with 4.4mm balanced cables because of a slightly better treble detail due to its dual DAC compared to the
Fosi Audio K7 which is a more neutral desktop amp.
Compared To
Sennheiser HD 800 S: this is superior in delivering a more natural sound staging. Vocals are centre forward, the left-right mix is more discernible, more comfortable to listen to in terms of imaging. Upper midrange is unforgiving, so the mix must be of audiophile quality or else it would sound unpolished. The i5 tonality is more refined, with more bass. Staging is closer, instruments less separated but still uncluttered.
Sennheiser HD 550/505: the i5 delivers better details without turning up the volume, because the 97mm diaphragm covers the entire surface of your ears, while the former is only a measly 38mm. For that, I can definitely hear the instruments and the timbre more clearly. On the
HD 550 or
HD 505, the overall sound presentation is more midrange-centric, more warm.
Hifiman HE400se: the
HE400se sounds comparatively feeble, more laid back, I have to turn up the volume more to get the HE400se to give me more impact. With the i5, I get details a lot easier, filling my ears with glorious music and the finer performance sparks.
Audio-Technica ATH-ADX3000: the treble is more transparent, sparkly, sizzle. The i5 provides more bass, the treble is less forward but remains sparkly at a lower intensity. Imaging-wise,
ADX3000 is more wide and separated, while the i5 sounds more naturally cohesive in the instrumental mix. The i5 sounds more full, the ADX3000 more spatial and airy.
Verdict
The Fosi Audio i5 delivers elevated bass without overpowering the highs, offers sparkling nuances without sibilance, achieves midrange details without muddiness. The headphones make timbre sound more distinct such that I can hear more tonality at moderate levels. It is also one of the few headphones where I can turn up the volume without feeling the pain, and when I do that, I hear even more precise attack and recorded decay.
While the headphones are quite heavy, the plushy earpads offer excellent padding and the headband gives me good support. I am surprised that I can wear them longer than some headphones at half the weight.
