I'm enjoying the X3. The interface isn't great but you get used to it and to me its about the sound first and foremost. Its a nice small good-looking DAP that takes 64gb (maybe even 128gb?) micro SD cards. So I'm really liking it, very clear sound and not too coloured (a bit less bassy to my ears than E17 even though its similar hardware on the amp side).
Check out this review on Headfonia for some good points on it
http://www.headfonia.com/first-impression-fiio-x3-dap/
They also reviewed an Ibasso that could be an alternative
http://www.headfonia.com/the-disruptive-ibasso-dx50/, or the AK100 / AK120 players seem to be getting a lot of love but a lot more $$$
M-100s Day2, still no comfort issues with the stock pads, very comfy.
I'm really loving the fun sound too. Also realised maybe my ears were too central, pushing the cups back so that the forward part of the pad is just on the edge of my ear seemed to increase clarity and soundstage a bit. So I would say try fiddling with positioning a bit.
I was just listening to this EP and literally dancing around the house in between shaving and doing washing etc. wearing them the whole time. Lol
http://hedflux.bandcamp.com/
HIGHLY recommended, guy is a sonic genius. I love Bandcamp and pay-what-you-want, always pay more for stuff I love
This was with the X3 on flat settings 0-0 and the bass was perfect, so tight and punchy for this type of dance music. The treble was clear but definitely taking a bit of a back seat. Increasing it to +2 on the X3 gave a tiny bit of extra sparkly without reducing SQ.
I think especially when commuting the bass on the M100 will be perfect. A good amount to block out outside noise and can always EQ to taste depending on the type of music.
Edit: Now listening to Mala in Cuba
https://soundcloud.com/maladmz/sets/mala-in-cuba-album-stream /
http://malaincuba.com/
MMMM BAAASSSS