So I was just browsing 64 audio official site for info about U12t and Trio, and from the tech spec it says these two iems incorporate LID technology, which stands for linear impedance design. As for the impedance descriptions, it's 12.6 +1/-2 ohms from 10Hz - 20kHz for U12t, and 5.5 +.5/-1.5 ohms from 10Hz - 20kHz, instead of the standard x ohms @ 1kHz descriptions. So is it some design they started with U12t and Trio, to achieve a flat impedance curve through all frequencies, or is it something they've been doing all along, but only decided to promote on it recently?