I mentioned this on the previous page but need to say it here too—CIEMs and UIEMs don't always sound the same. If anything, getting the two versions of the same set to sound alike is one of the hardest things to achieve for an IEM brand. As such, please be aware that my review of the CIEM version of the Custom Art Hybrid 3 Pro may not completely translate over to the UIEM version, but should be close enough to where you should get a good idea of either. I'd argue that Custom Art is one of those brands that you really want to go for a CIEM set anyway given how well they do it. There are so many customization options for the IEM shells, ear canals, face plates, logos, artwork etc and that is before I even realized the extensive configurator on the brand's website doesn't even cover all the possibilities! Take this review sample which has different face plates and shells than I thought possible. Custom Art says to talk to them about designs and materials you are interested in and they will work with you to make sure you are happy with your set. I will also give them props for using STL files of my scanned ear molds to generate two sets of CIEMs thus far which have both fit like a glove. This happened without ever having to use blank/test shells or having to send anything over physically so clearly these guys know what they are doing. CIEMs can take longer than UIEMs to make, for obvious reasons, with more bespoke designs taking even longer. In general, expect a lead time of at least two weeks. I believe this set took ~three weeks from the time I agreed to do the review to the date it arrived.

I will also reiterate how the booming IEM market, especially from Asian brands, has resulted in several Western brands being caught off-guard. Some simply can't compete on the more budget scale whereas many remain stubborn in putting out products that rely purely on brand heritage and awareness for sales. Smaller outfits that have started in the meantime have realized they need to keep pushing boundaries to survive, if not outright thrive. Custom Art was the first IEM brand to develop a flat impedance technology for IEMs which is extremely useful for music performers and engineers alike. Audiophiles these days are blessed with choice of several sources at different price points all having low output impedances but even then a set with 5 Ω impedance can be too sensitive for phones, laptops, internal sound cards etc. This way Custom Art ensures the Hybrid 3 Pro will sound the same no matter what you use it with. It's still not the easiest set to drive but that's again a non-factor for anyone with the budget for either the UIEM or CIEM version. Knowing there are only three IEMs currently being sold by Custom Art and having experienced all three, I can also tell you all three are very different sounding with different tonalities and technical chops. The Hybrid 3 Pro is the least expensive of the trio and yet happens to be the only set that attracts sub-bass lovers as well as those who generally prefer a darker sounding set.

The optional tuning kit can change the bass response of the Hybrid 3 Pro, especially the yellow filter which makes for a more neutral sound with near-flat bass, although I dare say the default brown filter already gives you a good taste of what the Hybrid 3 Pro was intended to sound like. There's a sub-bass shelf from ~150 Hz down which emphasizes electronic music in particular, and we then have elevated-to-warm mid-bass and lower mids alike. Using two separate dynamic drivers here works really well too with impactful and detailed sound that also comes off quite accurate. The upper mids and lower treble is quite forward facing, which can be good or bad depending on your preference, although I found it pushing the boundaries to be slightly fatiguing for me. Perhaps what made this worse was the highs were relatively recessed thereafter to further accentuate this presence earlier. This makes for an interesting set which works nicely for some music genres over others but also means it is harder to really get an appreciation for what the Hybrid 3 Pro can sound like simply by reading or watching a review. I personally preferred the FIBAE 5 and FIBAE 7 Unlimited more tonally, although I am sure there will be many who will be happier with the Hybrid 3 Pro instead.