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Kozee Infinity X3 Custom In-Ear Monitor Review

The info on Kozee Solutions is in the post above; the Infinity X3 is the top custom IEM offering that has 3 balanced armature drivers and a single crossover point for a 2-way system.  I chose the executive option, which has an acrylic shell, detachable cables, and upgraded drivers.  All drivers are upgraded, and the bass drivers are vented.  The standard option is made with a silicone shell and does not have vented drivers or a detachable cable for $50 less.  Each X3 (standard and executive) version is tuned individually for their respective drivers, and the vented drivers create a more spacious presentation according to Adam of Kozee.  Click here to see my custom IEM review, information thread, and manufacturer list thread.


Build Quality: The X3 shell has a great build quality free from bubbles with the exception of two bubbles by the right jack.  The Jacks are flush vs. recessed, but can be recessed upon request.   The cable is a twisted cable that is slightly thinner than your typical cable, but not by much and does not appear like it will affect durability.  It is very flexible and tangle resistant resulting in a great user experience.  The memory wire is a little on the long side as the tube is 3.375 inches long with the actual wire at about 2.5 inches.  This does make the memory wire more cumbersome to put on, and I think if it was between 1 to 2 inches total, it would be fine.  Overall build quality is very good.


Fit: I was very interested to see how the fit was going to be since I did my own impressions for the X3 (and TF10).  The fit on the left channel is fantastic and I thought the fit on the right was great, but after about 2 hours of use, the deepest part of the canal portion starts to become uncomfortable.  I have contacted Adam who wanted to resolve the issue and was fine proceeding the way I preferred (he has provided exceptional customer service so far).  Since it is a minor issue, I told him I was going to wait until my review was done and then send it in for adjustment.


Sound Signature: The overall presentation is forward with enhanced bass and treble that has a bit of a sparkle resulting in a non-reference presentation.  The enhancement to the bass is both in the ultra low bass and in the mid-bass.  The mids and treble have a slight analytical edge to them with an ever so slight grain on some tracks.  The overall balance across the spectrum in well done and reproduces the music as you would imagine they would be in front of you. All this is contained in a fairly well sized soundstage that while having very good width doesn’t quite keep up front-to-back and top-to-bottom.


Sound Presentation: The enhanced bass/mid-bass has good texture and detail, is tight and hits really deep giving a warm and hard hitting presentation.  The deep bass seems to be even more enhanced than the mid-bass as it is an experience with something like Massive Attack – Angel while the drums in Hotel California live have very good texture.  In comparison to the EP-10 Plus which uses a dynamic bass driver, the X3 bass seems to have more ultra low impact while there is much less mid bass, even though the mid bass of the X3 is also enhanced.  The X3 bass is tighter and they both have their own bass flavor, but due to the frequency response (without EQ), the X3 sounds technically better.


Mids have all the detail any universal can bolster and then some, being on par with the Fabs, but with select few vocal tracks such as Jheena Lodwick, the X3  adds slight grain.  There is also a slight analytical side to the presentation compared with the liquid EM3 Pro, SM3, and to a lesser extent, the Fabs.  Instruments are well articulated and placed within the space, even if they aren’t perfectly proportioned.


Treble continues like an extension of the mids (same driver?) and is presented in line with the mids.  While it is very present and seems to have a lower treble bump, it never leaves me cringing or wanting more.  The X3 treble is more present than that of the more expensive EM3 Pro, and placement is also different, with the X3 treble being more up front.   The Fabs treble seems to be presented about the same, however the rest of the spectrum is very different, so these two complement each other vs. compete with each other.


Presented space of the X3 seems on par with that of the Fabs, but when compared with the EM3 Pro, things were different.  For today’s popular music and electronic of just about any type the X3 had a larger presentation than the EM3 Pro, but for some music such as the Balmorhea, the EM3 Pro became very 3 dimensional and portrayed an atmosphere I have not heard with anything other than the SM3 to a lesser extent.


Comparing the X3 to the SM3 with custom sleeves, the presentation of the X3 is more forward across the spectrum, however the X3 is more spacious overall with more treble presence and sparkle along with more thunderous deep bass.  In addition, the X3 has more micro-detail than the SM3 along with a more exciting overall presentation.  I specifically compared the two with the Jheena Lodwick track from above and the SM3 is smoother at the expense of some detail, but also makes the voice sound a little deeper than it is.  The X3 will display some recording flaws the SM3 can hide.  To my ears, the X3 is a step up technically from the SM3, as it should be for the price, although the presentation is slightly different.  I would want to say it is more forward like the UM3X, but the UM3X seemed boring to me, and the X3 is anything but boring.  I would say the X3 is similar to the SE530, but the 530 seemed to have too much focus on the mids and too little deep bass and treble extension.  So the X3 IMO isn’t a direct step up from any universal I have heard.


Source Synergy: The X3 does great with lean/neutral sources such as my iPod and HUD-MX1, but doesn’t have good synergy to my ears with the 801.  The X3 does OK out of my laptop, however the lower quality DAC can easily be heard as the slight edge is increased to an edge!


Volume Performance: The X3, probably due to the sound signature, does quite well at lower volumes as the weakness of the EM3 Pro and Fabs is the bass drivers don’t seem to be pumping out their full amount of bass at very low volumes.  The X3 performs better from quiet volumes to loud volumes than any other IEM I have used!


Summary:  The Kozee Infinity X3 has a lush, rich spacious, forward presentation that I find very enjoyable for casual listening as well as using while working or working out.  The bass hits hard and deep with good texture, speed, and sustained note decay while the mids are presented in a slightly forward way.  The treble fits well with the rest of the spectrum rounding out the sound signature well.  There is a slight grain on some vocal tracks compared with my other customs and an edge to the presentation gets more apparent with lower quality sources.   I found the presentation great for pop and electronic music and is great for letting my music inspire me when I am focused on something else such as work or working out.   If you like bass heavy presentations and want the benefits that customs provide, the Infinity X3 is worth consideration.


NOTE: many people have had customer service issues, however I have not received any feedback in over a year from any of their customers.





Having a life-long love of high-quality audio and gadgets, average_joe got back in touch with his audiophile side after a hiatus caused by life. His focus became headphones and related gear as the size and price fit his life better than home audio. He believes the entire audio chain is important, and likes to continue to think past the headphone and on into the head, as he believes understanding the details of how we hear will lead to a better audio experience.


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