I am new to the headphone scene, and m9XX is my first DAC. There are two issues. This sounds clean and works well on my Window 7 and my son's Samsung S6 with Andriod 5 (connected using Inland On-the-Go [OTG] 2.0 USB to micro USB). However, the m9XX does not make any sound on Samsung Note II, Avant (both with Android 4.4.2), and Tablet 10.1 (Android 3) with the same set-up as the S6. I used OTG Check app to verify that the Avant does recognize the m9XX, but no sound. My carrier is T-mobile, and I take the Avant everywhere. Does anyone have the same issue with the Kitkat (4.4.2) or the phone carrier. Do I need to get a firmware update on my phone? Any suggestion? The second issue is sometimes, the m9XX have sound distortion when I initially plug in the USB 1. Then, I have either replug ged the cord or repower the unit. Does any one have the same issues?