I have listened to these more in-depth and here are my updated impressions.



I listened to them on my Samsung S9+ on loud volume, and with my large Spinfit tips which gives me excellent isolation and bass seal. To sum it up, I feel that the IOs are an otherwise excellent iem let down by a glaring midrange flaw, which makes the vocals sound weird. Here are the songs I listened to and my impressions:



Johann Johannsson - One Of Twelve

I use this track to test for bass and strings. This track has a string instrument (cello or bass I'm not sure) which goes very low and growls. It is one of the deepest strings I've heard on a recorded track. On the IOs, the rumble is lacking. The track also features a medley of violins. The IOs fails to capture the sharpness of the string instruments and makes them sound blunt, as though heard through a cloth/veil.



Rihanna - Lemon

I use this track to test for bass too. The bass is adequate and hits hard, which is a pleasant surprise for a dual-BA iem. At the 1:34 mark, the bass reaches extremely low to the point where it simply will not play on iems without deep bass extension (or most iems for that matter). As expected, I cannot hear much on the IOs unless I turn the volume up loud.



Album - Hybrid Classics

This album is characterised by overlapping layers of heavy acoustics, drumbeats, and strings. I use it to test whether an iem is dynamic, lively and whether it is able to separate the instruments clearly within the chaos. In "Formula of Fear", the baseline kicks in at 0:42. The IOs reproduces the drums and bass guitar very well, giving a sense of grittiness and head-bobbing rhythm. However, the vocals sound hollow, unnatural, muted and somewhat suppressed. This is to me, the biggest flaw of the IOs. The odd-sounding midrange makes the soundstage claustrophobic too. In "Break My Soul", in the climax at 6:08, the strings sound muted. I am not feeling the dramatic impact of the orchestra.



Overall, I would say that the IOs are excellent in dynamics. They have excellent clarity, instrument separation and can keep up with the many chaotic segments found in the album. However, the vocals sound horrible, and the string orchestras don't sound as majestic as they should be. The strings have an odd tone and are lacking in sharpness needed to bring the dramatic impact intended.



Andrew Bayer - A Brief Interlude

This song sounds like a movie soundtrack and contains a moving piano and string arrangement. I wanted to test whether the IOs would fare well on other string tracks after my experience with the last few songs. Same as above, the violins here lack the sharpness needed to convey the bittersweet emotions of the track. They sound clear but muted. It is as though the upper frequencies are being cut off or suppressed.



Fleetwood Mac - The Chain

The vocals sound harsh and unnatural. However, at the 3;24 mark, the IOs sound amazing. The guitar solo is full of energy, the bass is thumping and everything combines to form a lively engaging sound.



Ex:Re - New York

The cymbals here are very clear. However, the vocals sound odd and hollow. At 3:50, when the bass and cello plucking kicks in, the lower end of the song is lively. However, there is something odd going on. At the higher end of the song, the cymbals sound loud and clear, while the lower end is full of energy. The spectrum of sound in between sounds hollow and empty, which is made worse by the vocals. I don't know if my explanation of this is the clearest. The point I am trying to make is, this part of the song sounds so wrong and weird. It is as if something in the middle is missing.



K/DA - POP/STARS

While the energy of the song is well produced, the vocals just sound too harsh at times.



London Grammar - Everyone Else

I found the vocals on the IO weird. I wanted to test whether this is the same for all female vocals, hence I chose this track as the singer has powerful, throaty vocals that are unique. The IOs actually reproduces the vocals decently without the same oddness as on other singers.



Summary



Strengths:

-bass is adequate and has good impact. I would even say that it is one of the better ones out there when compared to other single/dual BA iems as it does not sound plasticky. However, when compared to dynamic drivers or more expensive BA setups like Campfire Andromedas, it is lacking in extension and rumble. I would not say that this is a flaw at this price range though as they already sound good enough to me.



-very good clarity and instrument separation. I would even say that they punch way above their price range. They have good dynamics and are able to keep up with complex, chaotic tracks which is rare at this price range.



-treble is clear without being harsh or spiky. Note that this iem is treble heavy and bright sounding.



Cons:

-the midrange is weird sounding and vocals sound hollow and unnatural. It sounds as if a random EQ setting was applied. On general, on many of the tracks I listened to, the female vocals sounded weird. On some rare tracks, the vocals sounded decent.



-strings sound muted and lack sharpness. They have an odd sounding tonality to them.



Conclusion

These are an otherwise excellent iem ruined by odd sounding midrange and vocals. On some tracks, they sound absolutely fantastic. However, once the vocals show up, they sound terrible. Without the vocal issue, I would say that they are a mini-andromeda because they sound excellent in most other aspects, for example their clarity and the ability to produce a lively, energetic sound. If you hide the vocals/midrange, they sound twice the price. I hope Campfire fixes the midrange and releases IO Version 2. It is such a shame to have an otherwise perfect iem ruined by vocals. The flaw in the vocals is glaring to me because 75% of my music contains vocals. I would say that if you listen to a lot of vocals, you may not like these. But if you listen to mainly instrumental tracks, for example acoustic or rock, you may enjoy these.



Someone new to iems may not hear the flaw in the midrange or get used to it because they may no have other points of reference. But for someone like me who have listened to over a hundred iems, the flaw in the midrange is very obvious. When you listen to them side by side with other iems, you can instantly hear that the vocals sound odd and hollow.