I just got my SMSL M400 and paired it with my Monoprice THX amp + HiFiMan Arya headphones via USB to my Mac with Audirvana. TBH, this is my first 'audiophile' headphone setup. I have a library of FLAC and MQA tracks, and I must say I'm BLOWN away! The sound is beyond amazing, and I'm very happy with the quality of the M400 minus the volume knob. SMSL seriously needs to upgrade the very plastic and wobbly feel of that knob. This is my first desktop DAC, so I can't offer comparison to other DACs. This is a keeper!