Don't be afraid of the impedance knob, set it to where you can get the volume you want. turn the iCan Pro's volume down all the way, turn the impedance knob to any setting, then turn up the iCan slowly. If it gets too loud, too fast, then go to a higher impedance setting and try again. The goal on most audio gear is to have your "normal listening" volume be straight up at 12 o'clock on the volume knob where most potentiometers are at their most accurate. I am testing an iESL right now and using a 200W amp and Stax 007. To have play in the preamp (volume control) I need to use either the 64 or 96ohm setting. 580V bias and "pro" setting on the AC Termination. This is with balanced connections which are almost 5V in my system so there's already less headroom. I can double my volume spread if I use single ended between the gear.