It’s not as much in the tuning, but remember that’s something that happens in general with most customs and the idea of a “perfect seal.”
I will say - 64 audio is notorious for some reason, having different tunings on their CIEMs versus universals. I’m not sure if this the case for the U12t vs A12t.
Hope someone like @Precogvision will be able to chime in with more info.
If that is too bulky, or I don’t want to carry around flagship IEMs, may substitute LCDi3 with Cipher cable for the DAC and IEMs
I usually use iPad 6th gen iPad mini as source, but can’t show Roon ARC well from inside my home net. the iPad has plenty of battery. Occasionally I use a powered portable dock for extended listening. If so, it’s usually connected to a large battery rather than wall power, as I find the Audeze LCDi3 and 4 sensitive to hum if connected to an AC power source. I did not have this issue with the plastic shelled iSINE 20.
Quick & Dirty rig would plug an iFi Go-Link into iPhone, and connect to Dunu Titan S or TruthEar Zero Red IEMs.
Background on photo is standard 8.5 x 11 paper, for scale.