Questyle Audio adhere faithfully to current-mode amplification at all form factors, and building a 4.4mm balanced output into the M15 just extended the capabilities of their flagship dongle. ecoustics rate it on par with legacy music players and "would suggest trying it before you pay for anything else". Headphonesty hail it as liquid gold.
It's easy to hear why, if audible results count to you. Operating in current-mode, audio signal gets passed in current instead of the more standard voltage. The Legend Evo from Empire Ears provides instant synergy, given its 3ohm load.
Current-mode amplification eliminates the lag time of the signal that might otherwise occur, as it builds up at the capacitances in the circuit – current signal passes through unhindered as compared to voltage, with speed and ease. [See Product Desc. For More]