The IT04 is a very refined and coherent hybrid sounding IEM. It has less of the brash musicality and emphasized tonal regions found in the IT03. Instead, it delivers a subtler u-shaped presentation rather than an out and out V-shaped musical presentation. With the IT04, there is a much greater emphasis on timbral accuracy, sounding more balanced and generally offering a more resolving performance.
A big factor in the presentation of the IT04 is the new graphene dynamic driver. iBasso have toned it down a little so it is not as aggressive or weighty as the IT03. It still has plenty of heft but the clarity is so much better. The layering is far more balanced to my ear with a tighter more defined response right down to 30Hz creating a more spacious sounding low-end. Critically, you feel less of a disconnect with the IT04’s mid-bass which retains a little more warmth than its smaller sibling.
Balanced Armature Tuning
The increased balanced armature count has also allowed iBasso to do a little more focused shaping in the mids and highs of the IT04. There is more of a 1-4k emphasis on the IT04, it will not sound terribly recessed at all, quite clear and clean actually. This is especially so with vocals which come across as little more intimate. The IT04 does not have the same level of body in its instrumental timbre as the IT03 but it does sound the more accurate of the two.
In my opinion, the level of tonal smoothness in the IT04 is down to how iBasso has shaped the FR to create a better overall harmonic balance. The slightly enhanced mid-bass levels, the forward upper mids, and an emphasized upper treble all serve to inject an even amount of upper and lower order harmonics that keeps that overall feeling of a presentation that sounds very coherent.
The IT04 low-end is very much a dynamic driver signature with a noticeable but pleasingly level of decay and a fantastic level of texture and detail. I so much prefer this driver to the older IT03 driver which offered even more sub-bass rumble and impact but felt softer, less defined and a little bloomier.
iBasso have not emphasized the absolute low-end as much which I think helps greatly keep it fairly open sounding. It still hits hard and offers plenty of impacts but the transient response is much quicker on the graphene driver so you actually become more aware of how well the low-end performs on the IT04, perhaps even more so than the IT03.
It still dips to around 700-800Hz by as much as 7-8db but its a slower dip than the IT03 which has maybe 2-3dB more sub-bass emphasis and drops to almost the same level in the lower-mids.
Lower mids on the IT04 as a fair bit behind the upper mids, by up to 8dB (in line with the sub-bass response). Lower-pitched instrumental positioning is a little behind vocals and percussive presence with a neutral level of body in their timbre.
The timbre balance though is very good. iBasso have pulled back on the lower treble presence that characterized the IT03 and let the 8-10k boost do the work of adding sparkle and odd harmonic clarity to both instruments and vocals in the mids. There is much less sibilance on the IT04 and far greater accuracy, particularly on percussion timbre which is clean, clear but never splashy or peaky.
A big change here over the IT03 and a smart one at that. The treble of the IT03 always gave me a little problem or two due to its emphasized lower-treble tuning around 5-7k. It introduced a level of partial sharp overtones with certain percussion heavy passages or bright recordings. I found it a little too “squeezed” or hot sounding when pushed too hard.
The IT04 is none of that. iBasso have gone in reverse by dropping the 4-6k region considerably and instead they have tuned for an 8-10k emphasis. This retains some essential odd harmonic clarity and ‘bite’ in percussion and higher pitched vocal timbre but deftly avoids sounding peaky and harsh sounding. It is a delicate balance but the IT04 has it more right than wrong. It also adds a little more extension in the staging of the IT04 over the IT03 so I tend to find it a touch airier sounding.
The IT04 is rated at 16Ω and 110dB which is a little more balanced in terms of impedance and sensitivity than the IT03.
Mind you I found the 107dB of the IT03 to in effect push up the volume considerably over IEMs with higher impedance ratings and this often led to me experiencing a little more peakiness on weaker amps also. With the IT04 you do need to push up the volume to similar levels but the tonal balance is now much more consistent.
Testing with an LG G6, FiiO’s X5iii, and iBasso’s own DX120 I found the IT04 usable volume range to be more than adequate but much higher than say an Andromeda or Hum Pristine’s all-BA design.
The noise level performance all 3 sources in unbalanced format (using the piggy tail extension) was excellent with a very nice black background and no hiss detectable using the IT04. Going balanced with the DX120 and DX150 using the AMP6 card also produced a very low noise floor indeed, virtually silent. The Cayin N5ii was also super silent in both balanced and unbalanced mode.
I did, however, detect a faint hiss or higher noise floor going balanced with the FiiO X5iii using the IT04 as well as portable amps such as the ALO Audio V5. The FiiO Q5 and iFi xDSD are also excellent pairings for low noise floors with the IT04.
Honestly, this is a very versatile sounding IEM. That balance and coherence in its signature means it does sound competent and well driven on just about any source I paired it with. It does not need huge levels of amping but a quality amp signal will produce moderate levels of scaling, particularly in the performance of its dynamic driver.
For example, going from single-ended to balanced on the Dx150 delivered a more refined and tighter bass response from the driver, even with volume matching to account for the increase in gain. To a slightly lesser extent, you get a bit more bass detail on the Dx120 also when going balanced over its single-ended performance with the IT04.
The FiiO FH5 is also a hybrid single dynamic and triple balanced armature driver universal IEM. They also use a 10mm dynamic driver though it is a PEK diaphragm as opposed to the Tesla 1W force graphene driver of the IT04. Both the Fh5 and IT04 use Knowles drivers, however, FiiO uses a mix of ED30262 for the mids and a dual driver TWFK-31082 for the highs whereas the IT04 uses 3 TWFK-30017 drivers across the mids and highs.
Design & Fit
The IT04 uses a custom universal design acrylic material compared to the FH5’s CNC tri-shell aluminum finish. This may not be quite as durable but it looks a little bit better for me and has a more accurate fit for my ears.
The IT04 is by the far the comfier of the two because of that recessed dip on the underside which neatly jumps my crus of helix ridge in my ear. The FH5 does pay homage to “custom universal” shaping and is very comfortable but does not have the dip which exerts a little more pressure on the ear.
Cables & Tips
Both have excellent tips selections. The IT04 has more, but the FiiO tips are better explained in purpose. The lip on the FH5 is a little bit better and holds the softer tips more securely. Both have excellent MMCX terminated SPC cables, to be honest. The big differences physically are the lack of memory wire on the IT04 and its stock balanced termination with the piggy tail 3.5mm add-on. It is a big difference maker for me in terms of options. The FH5 only has 3.5mm TRS unbalanced with no balanced options in the box.
The FH5 is rated at 19Ω and 112dB and is only marginally more efficient than the IT04. At similar volume levels the FH5 will be the marginally more efficient of the two and will go a bit louder faster but the gap is not huge. Both are easily driven from most moderate good quality sources such as their own respective line of DAPs and portable amps with the FH5 the quieter of the two IEM on sources such as the X5iii.
Tonally, the FH5 is a little “fleshier” sounding than the IT04, particularly in the instrumental timbre which is a bit warmer in tone and a little thicker in body. The IT04 has the better sub-bass clarity for me. The FH5 has the greater quantity and more mid-bass warmth so it hits harder but it is just a shade softer and not as well defined whereas the IT04 stays strong and clear.
Both have a very similar tuning bias to the upper mids however the FH5 starts to attenuate around 3k and stays fairly subdued in comparison to the IT04 right the way down to 10k save for a few minor treble bumps 7k and 10k. By comparison, the IT04 stays elevated up to around 4k and mutes the 4-7k range and then boosts from 8-10k.
The outcome is less air and height in the FH5 Presentation and less sparkle or extension compared to the IT04. Both avoid a splashy abrasive treble but the IT04’s upper treble elevation delivers a little more odd-harmonic crunch in percussion timbre.
The tone on the FH5 is thus more relaxed and rounded with more emphasis on width and depth than height. The IT04 has great depth, just not as much power or presence as the FH5, a spacious but neutral midrange, and excellent air and height. The FH5 is really more on the musical and forgiving side compared to the IT04’s cleaner and more neutral tone.
Campfire Audio Polaris
The Polaris is a triple hybrid driver universal IEM. It uses a slightly smaller 8.5mm dynamic driver with a dual BA configuration for the mids and highs. CA have also deployed their unique TAEC tubeless chamber design for treble performance. This is a system that worked really well on the Andromeda and trickled down with excellent results on the 3D-printed version inside the Polaris.
CA have also created a 3-D printed tuned internal chambers positioned to the front of the dynamic driver and another to the rear to maximize the 8.5mm driver compared to the enhanced magnetic force graphene driver of the IT04.
CA have reverted to their older anodized Cerakote angular shells from the Andromeda, Nova, and Orion for use with the Polaris. The fit is good, better than the Andromeda with the longer nozzle but not on the same level as the custom universal fit of the I04. The seal is also a bit better on the IT04 though with silicone tips the gap is much closer. Cable
Both use MMCX connectors but the materials differ slightly. I believe iBasso use regular brass connectors whereas CA uses their beryllium copper MMCX connectors which are longer lasting and more durable.
The Polaris uses a slightly cheaper copper Litz 4-wire compared to the 2.5mm balanced SPC and PVC finished 8conductor CB12s on the IT04. Personally, the build and performance of the CB12s are that bit better for me if you are into rolling.
The Polaris is rated at 16Ω and just 97.5db sensitivity. The I04 is a more efficient IEM and sounds a little livelier than the Polaris with similar DAPs on similar volume settings. Mind you, the gap is not huge. On the DX150 I had the IT04 on around 85 steps low gain and felt comfortable. For a similar level of liveliness, the Polaris was up to around 89-90 on low gain or around 2-3dB higher.
Tonally the IT04 has the more neutral sounding timbre, just a shade cleaner and lighter in terms of aggressiveness. Both have signature traits of a good dynamic driver with that excellent texture and detail. However, I find the IT04 low-end to be that bit tighter, better defined and just a shade quicker than the Polaris’s version.
The lower mids have a bit more of a dip than the Polaris with the CA tuning carrying a little more warmth into the lower mids. The IT04 instrumental timbre has slightly less body but is cleaner and more articulate sounding than the denser Polaris sound. Both have an elevated 1-3k (IT04 stretches to 4k) and do a good job pushing forward vocals. I tend to find the IT04 female vocal range to be more forward and fuller sounding whereas the Polaris did a better job with male vocal timbre which had a bit more body and presence.
Treble on the two IEMs is very different in tuning. The Polaris goes for something more similar to the FH5 though with a bit more extension and clarity. It is still fairly relaxed though with more lower treble focus around 5-6k but then rolls-off a bit beyond that. It has a tiny nudge at 10k but not much.
The IT04 greater upper treble emphasis means you do get a slightly cleaner sound but you also get more a bit more treble energy and sparkle. The interesting thing though I still find the Polaris to sound fairly open in the treble with a decent amount of air compared to the FH5, just not as extended sounding as the IT04.
Noble Audio Savanna
The Savanna is a 4 BA driver universal monitor retailing at the same price as the IT04. Noble does not release a whole lot of specs for their universal IEMs but we do know its around 30Ω and use specially tuned Knowles drivers internally.
The Savanna uses an aluminum top plate and acrylic bottom shell traditional rounded IEM design. It is eye-catching well-made and comfy but not quite as adept in passive isolation as the super svelte IT04. The seal on the I04 is on par with the Savana using the silicone tips but ahead on the foam tips.
Both are over the ear designs, however, the Noble Savanna uses a traditional 2-pin connector system compared to MMCX. We all have our preferences and I still love 2-pin and I do feel they have the longevity edge but the swivel and adjustment factor of MMCX is an advantage.
The cable on the I04 is much better than the Plastics One 4-core OFC black cable supplied with the Savanna. Rolling the cable on the Savanna to something more open and less resistive makes a big difference. The 8-conductor on the IT04 handles better, looks more eye-catching and simply sounds better. Balanced as the stock cable is really smart thinking from iBasso.
The Savanna is rated at around 30Ω but no listed sensitivity rating. Comparing with the IT04 I actually found the sensitivity rating to be almost the same with little or no volume changes required on sources such as the DX150/120 and 200. The Savanna is a little less sensitive to background hiss and noise on tested amps such as the ALO Audio V5 where it is virtually silent. The IT04 has a little more hiss using that amp.
Tonally, the Savanna is a very natural sounding balanced armature signature with an emphasis on a pacey articulated midrange, a slight mid-bass hump and a fair degree of upper treble boosting though nothing peaky. The big difference between the two is how they handle the low and high-end and their respective staging capability.
The IT04’s dynamic driver is far more powerful sounding though a touch slower than the Savanna’s BA presentation. The IT04 has more depth than the Savanna and will sound the more holographic of the two in terms of staging. The Savanna is lighter on its feet and well defined but lacks the rumble factor.
The IT04 also has more upper treble energy compared to the Savanna’s more intimate sounding lower treble focus. The Savanna has more of a sustained boosting from 5-8k compared to the IT04 which is stayed subdued until around 8k. Both have a tiny dip at around 4-5k though so percussion treble on both is not overly emphasized or harsh sounding.
Instrumental timbre on the Savana is a touch smoother than the IT04 and a little warmer. There is less of an odd harmonic presence in its vocals so they sound a little wetter than the cleaner IT04 delivery though neither have any sibilance.
The IT04 delivers a very refined and impressively coherent sounding presentation. It is iBasso’s more studied offering to date in their IEM range. That graphene dynamic driver has some excellent power but they really controlled it well to allow the rest of the range room to breathe and it is all the better for it. This is tight, defined, well extended and very spacious sounding. It has some zing in the upper treble and a nice forward clean sounding upper midrange which balances everything out nicely. The detail is also a good step up on the IT03.
You can tell iBasso are still refining that custom universal fit also. Nothing seems to stand still for them and the IT04 build quality is more evolved with a fit that is slightly better than the already excellent IT03. It also looks more polished than previous creations. The inclusion of the CB12s stock in balanced is one eye on the future with both 2.5mm and 4.4mm now possible with the IT04.
The IT04 will pair well with people who like that dynamic driver impact, texture and detail but does not want it forced down your throat. If you are someone who likes a clean top-end without harshness or sharp overtones with a good vocal performance then the IT04 is a really excellent and flexible choice.