I never said you need to be careful with the pot with the HE400, only sensitive headphones - the op never said he was going to use sensitive headphones - just dynamic in general. HD600, HE400, DT880, K701 are not ones I'd be thinking of here. You'd have to be careful with something like the HD598 or Philips X1.
But yes unless you are only sticking with the HE400 and dynamic mid fi with higher ohms go with something like a Audio GD or similar with gain switch.
I've run IEMS off an Audio GD and had 8-10.5 to work with which was more than enough for my listening range. How loud do listen to your headphones compared to others? I've had the HE500 off a Audio GD which is twice the power of the Magni and been good to go at 10-11 on the volume pot on many albums without trouble.
Edited by UNIFi - 4/20/14 at 3:00am