I have no clue about how it works but last night i hooked up my Senns HD650 and my Grado SR125 to my MK III with a Grado 2 into 1 (lossless splitter).
Here is what I found;
SPL meter showed at the same volume
Grado = 112...
I have the little dot mkii as well, paired with the little dot dac ii and grado sr125. They sound great; i put the GS1000 pads on the sr125's. This pushed the drivers out and made the soundstage huge. The senn HD650...
Little dott MKIII and Their Dac II
Grado SR125 (modified with larger circumural pads)
Last night I went crazy doing a side by side comparison. The HD650 are not yet broken in so it may not...