My star ranking is based almost solely on sound, which to me is the ultimate factor.
For this review I used the highly acclaimed new DAP called Onkyo DP-X1A, which uses twin Sabre 9018K2M chips, isolated DAC / amp sections, and a true balanced output. My source test tracks were in lossless FLAC format, of a variety of electronic, pop and rock genres. I used the same test songs which I am deeply familiar with, having heard hundreds of times including with many top-tier desktop rigs with highly acclaimed DACs, SS and tube amps, and numerous flagship headphones. (so I can pinpoint exactly how these songs should sound or if any nuances are missing).
My unit arrived with an almost supernatural speed, especially considering that I'm temporarily in a far flung Asian country (Laos) where they have never shipped to before. It took only 4 days to arrive at the local post office from Hong Kong, via HongKongPost, which I believe may be their preferred shipping partner. I've heard several others have received their unit surprisingly fast too, from New Zealand to the U.S. alike.
The B400's have a very distinctive look with stunning, almost futuristic looking curves, and especially look distinctive with the Blue Knight color I ordered, which I would call a deep blue with a nice shiny polish, and an overall robust look. This color is non-transparent, leaving that for the Stay Frosty version.
I also ordered mine with the Candy Cane 2.5mm balanced cable + Frosty Premium standard 3.5mm cable. With the Candy Cane cable, you get a super pretty array of red, blue and silver colors in a very lightweight package. The Frosty cable is is equally radiant, perhaps enough to get a compliment from a fellow passenger. Both are ultra flexible and lightweight, and have virtually 0 microphonics, or at least not noticeable to cause any concern. Surprisingly, the balanced Candy Cane cable is about the same thickness as than the Frosty cable, if even possibly a nuance thinner.
Included were what appears to be 2 pairs of 3 sizes of silicone eartips S / M / L, plus Comply T-100 red.
Being a very well designed universal-fit IEM, these should have no problem sliding into most people's ears. They feel very smooth and almost as if 'invisible', however after 2+ hours of consistent use my ears do start feeling somewhat sore - as is with many IEMs too.
The pre-installed eartips (small perhaps) worked best for me from the ones included, but after trying all sizes somehow none of them were getting an optimal seal for my ear-shape, indicative of my hearing a void where the bass should be. Tried on the Comply tips and got a fuller bass, yet as mentioned by others and as I have observed on numerous occasions - foam tips have a tendency to mess with or 'smear' the treble. Also as I've experienced with a variety of foam tips they also mess with the bass giving a somewhat overtly laid back / un-detailed sound - at the cost of more balanced isolation. Next I tried a pair of standard silicon round Spinfit eartips, and much to my surprise these did NOT gel well at all with the B400's. Somehow either the angle of the nozzle or somewhat shallow insertion depth of the B400's did not allow these to seal at all. Although it may be possible standard Spin fit tips could fit another's ear depending on their shape, or that another Spinfit model such as their dual-flange version which I would ascertain may be better. Luckily I also brought along a small collection of assorted generic eartips from other IEMs models, and was able to secure a very good seal and level of isolation (photo with preferred tips below).
Considering the B400's already have a fairly thin nozzle, I recommend that using eartips with a slightly wider bore width would improve the sound somewhat. Indeed I was definitely hearing a somewhat fuller and overall more resolving sound with the chosen generic eartips from another brand, which may have been not only due to the wider bore, but also from what seems to be a perfect seal.
I didn't notice much of a difference in comparing the 3.5mm standard to the balanced cables. This was somewhat of a surprise to me, especially considering the staggering difference I heard previously when upgrading to a balanced cable on another IEM model using the same source; of which results were improved dynamics, realism, soundstage and texture on an unwavering and repeatable basis. Due to difficulty of removing the MMCX cables on this unit, I won't be comparing these two types since I will likely be leaving on my balanced cables.
OVERALL SOUND IMPRESSIONS
I would describe the sound of the B400's as laid back and non fatiguing. Slightly dark and mid-centric leaning with a nice seductive lushness. These are by no stretch of the imagination 'analytical' such as the Ultimate Ears 18 with 6 drivers per side nor the HD-800 full size 'cans, but rather mellow and pleasing for nice long listening sessions. The sound is moderately vivid, but with less realism and 'slam' than other IEMs I've heard. I would compare their sound with the full size Sennheier HD-650 headphones, but slightly more 'front row' sounding.
A main reason for my calling these laid back is because of their bass definition, which in my tests has shown to be quite boomy and boxy, or somewhat 'muddy' and quite lacking in texture. Hence also the reason I mention somewhat mid-centric, because to my ears at least, the sub-bass has a certain roll-off in the lower registers. Interestingly the FR graph below shows it to be very well extended, but no matter how perfect of a seal I was able to get or by EQ'ing the low frequencies, I seemed to be unable to get any 'subterranean rumble', as they call it; lower sounds that were evident to me on several of my comparison IEMs mentioned below.
On the positive side however, its' bass has a certain quality that can be fairly pleasing to the ear, in a somewhat 'fun' way, and can still sound quite good especially for a semi-bright recording. After the multi-hour listening session above and coming back later in the day for a fresh listen, it becomes clear to me that the only reason I had noticed anything even slightly off about the bass is because I had been a little, well... spoiled (Lol) with other IEMs to compare it to. A casual listen may not reveal anything untoward with the bass, until after directly comparing it to other models which I noticed a more resolving / fast and well textured bass by contrast.
The mids seem to be their strength, giving a very pleasing, tonally correct reproduction and a nice 'voluptuous' lushness. These also make vocals sound very nice.
The highs are very organic and natural sounding, and linear meaning not boosted or recessed. They do however sound to be rolled off somewhat early in the higher regions, losing some of the upper shimmer and detail.
The soundstage is acceptable - definitely larger than almost any straight-form bullet-shape earphone I've tried, but about equal to the average IEM. I am however hearing a decent amount of depth as well as width.
To me, this is one of their weak points. The transient response seems somewhat slow, and I'm not hearing the same amount of 'snap / attack' as with other headphones and IEMs. Certain drum sounds are hard to discern in the mix, which are easy to pinpoint on other systems. Myself also a great fan of electronic music, the drums generally don't have enough 'kick' to sound correct, but can sound pleasing depending on the recording.
Stereo width / realism
While the actual stereo width is not an issue nor stereo imaging, in my tests I seemed to notice something a bit off kilter in it's reproduction of stereo sound, almost as if an artificial stereo expansion effect was applied, and sounds moderately congested. The other somewhat related factor is what I call 'realism', referring to how 'lifelike', realistic or natural of a sound; and otherwise how much 'energy' and 3D extrusion it has, as I call it. While I can provide no input on how to design an IEM these attributes differently, I can only say that this is one area where it's fairly lacking, contributing largely to the laidback sound. (more on comparisons below).
The B400's have an outstanding ability to handle complex recordings, most likely in large part from their quad drivers. It handles the most complex recording I threw at it with great finesse.
(multiple separate critical listening sessions were done on volume matched looped sections of test tracks)
RHA T20 (non-mic version) ($192)
The RHA has a more liquid, sweet, detailed and organic sound, and overall brighter. Mids that are more vivid and textured, vs. lush mids of the B400. Dynamics are punchier and bass extends deeper. Treble however being more extended is at fault here, with a somewhat artificial quality, whereas the B400 has a more proper tonality.
TFZ Exclusive 1 ($45)
The TFZ has an unmistakably tighter transient response / dynamics, detail retrieval and imaging - all on the order of 2x more than the B400. The bass extends noticeably deeper into the sub-bass realm, and has an amazingly realistic 3D extrusion with layers that jump out at you. The simple, unassuming design of the Exclusive 1 packs a mighty punch with ultra realism, spot-on imaging, superb detail, transparency and buckets of sonic texture that can even invoke an emotional response. It is a completely different signature than the B400, being notably brighter / faster / more extended; the B400 sounds more pleasing for pure vocals, and for brighter recordings. Bearing the "HD resolution" label, this is a rare entry into its' price-point. Occasionally the highs can be moderately fatiguing, but that's more because of the balanced silver cable I'm using, whereas with the stock cable the sound is slightly warmer. I also tried the TFZ Exclusive 2 and 3 but found them quite unbalanced FR-wise. Size of soundstage is similar on both.
Advanced M4 ($40)
Comparable to the B400, but with a different overall presentation. Bass seems to extend to a similar depth as the B400, but with slightly less mid-bass hump. Detail and imaging are also similar to the B400. Treble is nice yet not extremely extended, and dynamics are punchier. Overall a more 'dry', flat and slightly anemic sound than the B400. The M4 sounds quite pleasant with rhythmic electronic music... so does the B400, in a more laid back, tonally correct and lush kind of way.
These are quite similar in price, form and sound to the Zero Audio ZH DX240CI.
(by memory - take these with a grain of salt)
Focal Sphear ($89)
Compared to the B400, these had an artificial quality to the treble and mids, though modetly faster transient response, and possibly smaller soundstage. Very shallow insertion, making fit difficult.
Ortofon e-Q5 ($210)
These Ortofons were to me an absolute abomination to the hi-fi hobby with destructively non-detailed, muddy, congested nasal sound and major steps back in every aspect especially detail. The B400's are light years ahead of this one.
JVC HA FW03 'woodies' ($220)
Quite brighter and 'faster' than the B400's with a more vivid, colored almost 'euphonic' tone, with improved bass definition and overall texture, however perhaps too bright, and seal was near impossible due to very shallow insertion. I liked this one better than all the other JVC 'woodies'
Radius NHR31 ($140)
Rare find with sweet, fluidic, smooth mids & treble, well extended bass and very lifelike and punchy. Shallow insertion also made seal quite difficult, and may have had a slightly 'off' tonality. Further testing required, yet this one was to me the best of the entire Radius line including their higher models. B400 isolates much better.
I've also recently had the rare chance to audition approximately 250 IEMs of all brands spanning several days at some of the world's largest earphone shops in both Osaka and Tokyo, so I can attest to the fact that the B400's compete quite well around the $200 range, with perhaps 1-2 extremely rare fluke exceptions that may surpass their performance. As with headphones, no IEM does everything absolutely perfect, even including the TFZ 1.