Sound Analysis.

After confirmation of the fitment, I was ready to start my sound evaluation.  Since I don’t have any previous experience with other Custom Art CIEMs, I wasn’t familiar with their house sound and didn’t know what to expect.  But knowing that I’m dealing with 4 dedicated bass drivers and 2 dedicated tweeters, I was already anticipating great things from the low end!

With hours of careful listening, I found Ei.xx to have a smooth detailed sound with organic tonality and enhanced low end impact which contributes to a slightly v-shaped signature.  Here is my sound analysis in more details.

Considering 4 dedicated bass drivers, 2 super lows + 2 lows, you can take a wild guess that bass is a star in these CIEMs.  Ei.xx low end is very articulate, tight, well controlled, with a deep textured sub-bass rumble that is not just great in quality but also in quantity, and at the same time perfectly balanced with a fast mid-bass punch.  In this case I’m “hearing” low end performance like a hybrid combination typical of dynamic driver longer decay (down in sub-bass area) and a fast BA punch with a short attack (in accentuated mid-bass).  There is a very slight bleed into lower mids, but it doesn’t contribute to any muddiness.  With such attention to low end details I don’t want people to think Ei.xx is a basshead CIEM, but for sure it will be highly appreciated by anybody who craves high quality articulate bass impact.  If you are a fan of SE846 and UM Pro 50 bass – Ei.xx will be not just your cup of tea, but the whole kettle!!!

Lower mids presence is not too thin or too thick, sharing a little bit of warmth from the low end which adds some body to a sound.  Upper mids are smooth, detailed, and very organic.  They are not analytical or micro-detailed, but they do have a good level of clear detail retrieval while still remaining smooth and natural, especially with vocals (both male and female) that shine through with a clean timbre.  I usually trust my ears over FR measurements, but was curious to see Ei.xx FR graph where I found a slightly scooped mids around 500Hz-1kHz which explains why mids sound a bit recessed.  You have 4 drivers dedicated to low end and 2 dedicate to top end, and the valley of that scoop actually partitions low end and top end into their own separate domains where you can shift listening “focus” from one to the other.  I actually found this slight scoop to enhance the dynamic impact of the bass and to improve the clarity of upper mids.

Despite 2 dedicated tweeters, I found their sound tuning to be shifted more toward upper mids and lower treble range.  Treble is smooth and detailed, not extra crisp or super “hi-def” extended, and also lacking some airiness.  But at the same time it has a rather good definition, and absolutely NO sibilance which is fantastic for extended listening sessions.  I threw at Ei.xx all my sibilant test tracks, and it passed the test with flying colors.

Separation of a sound in these headphones is good, with a clear layering between vocals and instruments, preventing congestion of a sound.  I was also impressed with a soundstage expansion, definitely way above the average.  Actually, I’m hearing more width and height than depth.  To my ears, placement of instruments and vocals was not exactly 3D in space, but it still had a very convincing natural imaging with some intimacy.  This type of imaging along with a smooth detailed sound would make Ei.xx not only great for audiophiles and casual sound enthusiast, but also for performing artists to use these CIEMs as monitors on stage, which is great for extended listening in any environment due to a great isolation and very comfortable fitment.

When it comes to pairing, I’m not going to talk about every single DAP I tried it with because I have way too many of them.  But one thing I found in common – a warm smooth signature won’t benefit from a warm sound source which can make sound more congested and less detailed.  I found Ei.xx to pair up better with neutral and brighter sources.  No amping was necessary, and due to sensitivity you will enjoy these better with sources that offer a solid black background.

Comparison.

In comparison to some of my other IEMs, here is what I found.

Ei.xx vs P650 – P650 has a very similar soundstage expansion, sub-bass doesn’t extend as deep and has lower quantity, mid-bass punch is not as tight and overall bass is slower and lower in quantity, and not as well controlled.  Lower mids are a bit thinner, while upper mids are a little more upfront.  Treble is slightly better with a little more brightness and airiness.  While fitment should be similar (due to impression from the same audiologist), P650 felt a little less comfortable in comparison to CA.

Ei.xx vs SE846 (going by memory when I had a loaner, while I took good notes) – 846 low end is very similar in terms of the impact, speed, and overall emphasis.  Ei extends deeper with a more noticeable sub-bass quantity.  Also, Ei mids are more organic and smoother, while SE846 mids are more in your face, brighter, and a bit harsher to my ears.  SE treble has more airiness, more sparkle, while Ei is smoother and not as extended.  Soundstage is similar.

Ei.xx vs UM Pro 50 – Pro50 soundstage has less width, mid-bass punch is very similar, but Pro 50 sub-bass doesn’t extend as deep and doesn’t have the same level of rumble, and feels a bit scaled down in comparison.  Lower mids in Pro 50 are warmer/thicker, while Pro 50 upper mids are similarly smooth and organic, and maybe a touch brighter.  Treble in Pro 50 is a bit brighter, has a similar definition, and a little more airiness.

Ei.xx vs W60 – W60 has a similar soundstage expansion, bass is less aggressive, more laid back (slower attack), and less quantity.  Similar low end extension, though Ei feels like it goes a bit deeper, and the mid-bass punch is tighter and better controlled.  Lower mids are very similar, while upper mids in W60 are more detailed, have more natural tonality, and a little more upfront.  Treble is very similar.

Ei.xx vs W50 – W50 has a touch narrower soundstage, very similar low end quantity with a similar deep sub-bass extension and slower mid-bass punch.  Actually, W50 bass sounds looser and even a bit muddy, not as articulate.  Mids are warmer and thicker, not as detailed, while treble is similar.

Ei.xx vs DITA (silver gold re-cabled, original sig is changed) – DITAs soundstage is a bit wider, sub-bass has a similar extension but less quantity, mid-bass is not as punchy or as fast, sounds slower.  Low end is not as tight or well defined, too relaxed and lower in quantity, lower mids are similar, but upper mids are a bit more recessed and brighter in comparison, treble is brighter, more airy, with a better extension.

Comparison to W60, W50, UM Pro 50, DITA (Whiplash cable mod), InEarz P650, and SE846.

Conclusion.

IMHO when you are dealing with a quality $500+ multi-driver IEMs/CIEMs, it’s no longer about sorting out “bad” vs “good”, but rather about discovering different sound signatures to determine which one you enjoy better or which one comes closer to your preference of TOTL end-game sound.  The more headphones I review, the more I realize that TOTL “end-game” sound encapsulated in one pair of headphones might not be realistic.  Not necessary because it’s not possible, but rather because I end up craving two types of sounds (Yin-Yang): a smoother/warmer/organic with more bass impact and a more neutral/brighter/revealing with a more balanced signature.  It all depends on my mood, on the type of songs I’m listening to, and the sound signature of sources I’m using.  To my ears Ei.xx sounds like a love child of SE846/UMPro50 (low end impact) and W60 (organic detailed smoothness of mids).  It definitely takes Yin to perfection and makes it one of the new reference standards in my book when comparing bass quality and quantity, along with a smooth detailed organic mids/treble.  I might be still on a journey to find my Yang where most of the revealing IEMs I tested had some harsh peaks (subjective to my ears), but in case of Yin I found Ei.xx to hit it hard with a bass impact like a jolt of energy!  Well done Custom Art, well done Piotr!  I’m looking forward to your next masterpiece, perhaps something that can bring my Yin and Yang closer together under one roof (or in one shell).