Hi friends, for some of my low impedance and high sensitivity IEMs, I get a hiss with smartphone and desktops. But it disappears with an inline volume controller or impedance mismatch device or an amp. This hiss is more marked in some IEMs than others (using the same source and same 8 core copper cable from NICEHCK): These are my IEMs with hiss: - TFZ No. 3 (impedance 20 ohms, sensitivity 108 dB) - KZ ZS10 Pro (impedance 30 ohms, sensitivity 111 dB) No hiss: - Audiosense T800, (impedance 9 ohms, sensitivity 90 dB) - Toneking nine tails (impedance 16 ohms, sensitivity 100 dB) - Hisenior B5+ (impedance 20 ohms, sensitivity 102 dB) - Westone W30 (impedance 30 ohms, sensitivity 107 dB) - Semkarch SKC CNT1 (impedance 32 ohms, sensitivity 108 dB) Is hiss factored by both low impedance and high sensitivity? Which is more influential in hiss among the 2 factors? I'm no audio expert, but I'm wondering how come the IEM with very low impedance (9 ohms in Audiosense T800) can have no hiss compared to the 30 ohm KZ ZS10 Pro with hiss? Would appreciate any advise, thanks in advance!!!