This and That:
I really like the design. Good build quality as well. Side-markers easy to see.
Cable rather decent although not the that supple.
Sound:
Low impedance sources, only included black silicone tips.
Tonality:
Bassy, warm and especially very dark. Not much treble to begin with. Like a downwards sloping line from the lows to the highs with a difference of more than 20 dB (that's a loudness differenc between the lows and highs of more than four times!).
Everything sounds like behind a thick curtain or blanket. Noticeable bass bleed into the midrange. Treble way too dark, lacking any clarity.
Taking my Etymotic ER-4S as a reference for a diffuse-field neutral bass, M100’s is a little more than 11 dB more present.
To my ears, listening to music and a sine generator, the lows’ emphasis starts somewhere around 900 Hz and then climbs up with the shape of a hump and is already quite full between 200 and 300 Hz. It however continues to climb, although not by much, and reaches its climax a little below 100 Hz. To my ears, the bass doesn’t really lose any presence towards the sub-bass.
It is an overall very full sound with a strong and warm fundamental range that clearly bleeds into the midrange and makes voices sound very thick and full.
Unfortunately the level continues decreasing between 1 and 2 kHz, which results in the midrange also becoming dull and muffled sounding.
The rest of the treble is noticeably in the background and very dark. To my ears it gains a little presence around 5 kHz where it is however still clearly the background. As for the rest of the highs, they are still audibly recessed. Cymbals sound quite muffled, too.
This in-ear clearly lacks treble and brightness. It also suffers from a severe bass and warmth bleed into the midrange.
I do like some warm, dark sounding in-ears and headphones, but the M100 goes way overboard and sounds just muffled, muddy and dull.
Resolution:
Nothing special and outperformed by several other similarly priced in-ears.
Not the fastest sounding in-ear but soft and slow on fast and busy tracks. Not too spongy but clearly not tight or precise either. Also softens up towards the sub-bass.
The amount of details in the midrange and treble is not too bad and about average. The overly smooth and dark tuning without any harshness or peaks can then even sound quite nice, nonetheless the M100 doesn’t have the best separation or refinement with busier tracks that are either faster or feature many tonal elements or musicians.
The combination of the tuning and the rather soft and slow appearing driver is definitely not the most convincing pairing. Okay for $30 to $50 but not for around $100.
Soundstage:
To my ears, the M100 doesn’t have the widest nor the narrowest soundstage but seems rather average in terms of lateral expansion. Depth is almost as present as the width and one can also sense some layers, nonetheless there is no/only very little air or empty space around instruments and the overall presentation appears rather foggy, especially with busier tracks.
Conclusion:
Very little treble. Sounds dull, foggy, slow, muddy, soft and muffled.