If the V20 dac is designed to work with a impedance of between 50 and 600 ohms are we really getting the most out of it. I own several pair of headphones and iem's from Beats to Sony to Vmoda and none of them have a impedance that high so are there any headphones on the market that offer a impedance between 50 and 600 ohms since that the sweet spot of the V20 dac.