Sound of M4 is just exquisite! Very flat, with good monitors. Revealing all tiny details in recordings. No noise at all. I was replacing my older Focusrite Saffire, which sound just muddy and boring in comparsion. I can hear now sparkly highs and deeper lower ends with ease. Also its seems that my Genelec 8010 can go a tad lower, with M4, excelent!
However im missing some kind of cue mix app, would like to have more control in in/outs. Also 3/4 inputs are only line level, which is very low for most cases, dont understand why MOTU chose this design, would love to have switchable with line/INST level inputs. Also 3/4 inputs are stereo only, why MOTU? Will be ace to have 4 individual mono inputs. Oh well, maybe in next FW?