Yes, the custom version is very different. I'm sure that a lot had to do with the seal, and possibly how close the tia driver is to your eardrum. But I can say that on the custom version, the bass, hits harder, the subs are more present, I think even more than the trio in quantity and high frequencies are smoother as well. I didn't like the high frequencies on the U12t, something just sounded off. In the end, I couldn't get the U12ts to sound good with any of the included tips (the included silicon are a waste in my opinion), or any of my spinfits, symbios and other tips I had. Makes me wonder how a custom trio would sound, because I really liked the trios, but personally, I prefer the custom version of the A12t, if I could only have one. It also had fuller mids than the trio. In an ideal world, I'd own both though
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