Recently I just sold away my SR-71, TBH and minified PINT to fund some new purchases. I thought I wouldn't be needing any portable amps to go with my IEMs, so I stupidly sold them away. I am looking for some new portable amps to try. Now I got a pair of RS-1 and MS-Pro, thinking to bring one...

My friends use sony EX-81, shure e2c on their iPods, however, they crank up the volume to 50-60%. But for me, I used ER6i with my iPod, I just listened to maybe 5-10% of the volume in a noisy environment. Why is that so, is it because the low impedance and higher sensitivity of ER6i? Another...