The iBasso IT04 is a hybrid in-ear monitor with one graphene diaphragm dynamic driver and three balanced armatures on each side. The IT04 retails for $499. I received the IT04 through Headphones.com’s Community Preview Program and will ship the IT04 back shortly after this review goes live.
This review can also be read on my blog: iBasso IT04 Review
SOURCES :
I have used the iBasso IT04 with the following sources:
- JDS Labs The Element
- Apple USB-C to 3.5mm dongle
I have tested these headphones with local FLAC and Spotify Premium. Visit my last.fm page to get an idea of what I listen to.
PACKAGING AND ACCESSORIES:
The iBasso IT04 comes in a rectangular black box with a white slipcover. The IT04 is pictured on the front of the slip cover. The back panel of the slipcover lists the IT04’s technical specifications in eight different languages. Inside the box is a large round screw-top metal case containing the IT04 earpieces, a black cardboard box containing a braided detachable cable with MMCX connectors and a 2.5mm balanced termination, a 2.5mm balanced to 3.5mm single-ended adapter, five sets of silicone eartips in varying colors and bore sizes (S, M, L), and 1 set of foam eartips (M, L). The metal screw-top case will not fit the IT04 unless one removes the foam insert.
BUILD QUALITY / DESIGN:
The iBasso IT04’s teardrop-shaped, pseudo-custom fit earpieces are made of glossy black plastic with blue-grey carbon-fiber patterned face-plates behind a clear laminate coating. The faceplates are marked with the text “InTune” in silver script and “iBasso Audio L/R” is printed in white text on each shell. The shells are likely the largest of any IEM I’ve worn. The shells have two circular vents on the ear-facing side, one at the base of the nozzle and one in the center of the shell. The IT04’s nozzles are plastic with metal mesh protective grills. The nozzles do not have a lip for securing eartips, but I did not have any issues with tips coming loose in my ears while using the IT04. The right side earpiece had significantly worse driver flex than the left side earpiece.
The IT04 comes with a beautiful mixed silver and copper MMCX cable. The MMCX connector housings, chin slider, Y-split, and 2.5mm jack housing are all metal. The MMCX connector housings are labeled “L/R.” The braided cable does not have pre-formed ear-guides or memory wire. The cable is not tangle-prone or microphonic. There is strain-relief above the straight 2.5mm jack and below the MMCX connectors but none at the Y-split. The 2.5mm to 3.5mm adapter uses the same cabling and hardware materials and has strain relief above both terminations.
COMFORT / FIT / ISOLATION:
The iBasso IT04 is intended to be worn cable-up only. The large size of the shells makes them uncomfortable for me to wear for more than an hour or two. The nozzles provide a deep enough insertion depth to facilitate a good seal with all of the included eartips. Secureness of fit and isolation are both above average.
MEASUREMENTS:
My measurements were conducted with a Dayton iMM-6 microphone using a vinyl tubing coupler and a calibrated USB sound interface. The headphones are driven using my Element, which has an output impedance of no more than 1 ohm. The measurements use a compensation file derived from relating my raw measurements to published measurements from Crinacle and Antdroid. The measurements are presented with 1/24th smoothing. The magnitude of the valley around 7k is a coupler artifact. There is a resonant peak around 8k. Measurements above 10k are not reliable.
I have measured the iBasso IT04 under two test conditions. The blue line is a measurement taken with the vent closest to the nozzle taped over, while the green line is a measurement taken with the vent uncovered. As shown, the IT04’s frequency response varies wildly depending on the degree to which the vent closest to the nozzle is covered. Depending on the tip used, the insertion depth, and one’s ear anatomy, one can get a completely different sounding IEM depending on the degree to which the vent is blocked.
Below is a measurement under ideal conditions, where the nozzle-adjacent vent on each IEM is completely taped over:
I think it is a poor design to require the nozzle-adjacent vent to be completely covered to get what I assume is the intended, non-anemic bass response and an uncompromised upper midrange. Even putting that aside, I expect better channel matching from a $500 IEM.
SOUND:
Under the ideal conditions described above, the iBasso IT04 has a U-shaped tuning with a strong lower treble emphasis.
The iBasso IT04 has excellent sub-bass extension. The lowest sub-bass is more prominent than the mid-bass. There is a fair amount of impact, slam, and rumble. The bass has very good speed and articulation but does not sound as effortlessly quick as more recent offerings utilizing diamond-like carbon diaphragm dynamic drivers. The IT04 has excellent bass resolution. Bass texture is good but not stellar.
The midrange has a slightly cool tonality. Instruments in the lower midrange have adequate body but clarity is emphasized over warmth. Female vocals are a tiny bit more forward than male vocals. Male vocals are conveyed with grit but are slightly dry. Female vocals are rich and vibrant without being sibilant or overemphasized. There is a healthy amount of presence.
The treble prioritizes sparkle and detail retrieval over spaciousness. This lower treble emphasis can be too pronounced depending on the recording but is not usually harsh. Treble transients are quick and do not smear. There is limited air.
Soundstage is larger than average. Imaging and instrument separation are very good. Timbre is mostly realistic if cool and slightly dry.
AMPLIFICATION REQUIREMENTS AND SOURCE PAIRING:
The iBasso IT04 can easily be driven to comfortable listening volumes with a smartphone or dongle. I did not notice hiss with either of my sources.
COMPARISONS:
iBasso IT04 vs Tanchjim Oxygen
The Tanchjim Oxygen uses a single diamond-like carbon diaphragm dynamic driver. The IT04 has more prominent sub-bass than the Oxygen, with greater rumble. Impact and slam are roughly comparable between the two IEMs. The Oxygen has a faster, better-articulated bass with slightly greater texture. The two IEMs have similar bass resolution. Female vocals sound slightly more vibrant on the Oxygen. The Oxygen has a more even treble presentation with a more restrained lower treble region and more air in the upper treble. The Oxygen has a much smaller shell size and is more comfortable for me to wear for long periods, but requires extensive aftermarket tip rolling to get a secure fit. The Oxygen has a slightly larger soundstage and better imaging. The Oxygen is harder to drive. The IT04 comes with a much nicer cable and a more impressive set of accessories. The Oxygen uses slightly recessed 2-pin connectors instead of MMCX.
CLOSING WORDS:
Under ideal conditions, the iBasso IT04 is a highly detailed and resolving IEM but its shell design may not be comfortable for all listeners. However, I do not feel it is a reasonable design assumption to rely on the nozzle-adjacent vent to be completely blocked by variable ear anatomy in order to get the intended frequency response. Not recommended.