I just got mine today, my first impression their real close to the M-50 than A900x.
It's missing "Air", one of the reason I love the A900x is the Air to Bass combo it's just right for my ears.
Will burn them in and see if they change in sound to me.
What source are you using with them? Are you using mp3 or flac ect...I use my AD900x as my commute headphones, DX-50+C&C BH2 perfect match for my ears.Also when i use AD900x with my Iphone5 i can hear the bass.
I had the headphones your talking about around the time I bought my DX50.
Your going to like either DAP they are both way better than Samsung Galaxy.
My commute rig DX50+C&C BH2+ATH A900x=Love
Hope this help.