As always, I put in about 50hrs on the IEM before the review though didn’t really notice any significant change in sound characteristic. One of the first things to notice on M1 is the ‘house sound’ carried over from M2. It is the same warm and musical presentation that makes the M series easy on the ear and appeals to people who are looking for musical experience as a whole but not a mixture of notes.
The overall sound signature is warm, smooth, musical while a little laidback. Treble is decently extended but doesn’t have a lot sparkle, smoother than that of M2. Mid is full and vocal is quite sweet. Bass has good body and decent impact though just a tad slow and mellow out the general sound impression. Above average soundstage but limited by its inabilities to present good airiness and form a detail image.