You are trying to drive a low impedance, low sensitivity planar with portable dac/amp or entry level dac/amp. If you are happy with the result, no one is stopping you from listening to your cans. Would I use $2k difficult to drive planar with entry level stuff, god no. There are more appropriate cans that cost both less and more than E3 that would be better suited to those kind of electronics.
People are also free to buy E3, Stealth, Susvara or any other pair of low sensitivity cans and use laptop headphone jack. It's a waste of money IMO but you do you.