Perhaps you purchased the wrong dongle, its a great device but due to its specs and features its not for the lighthearted Head-Fier.Dc-Elite is here.
Small problem related to Android, the volume on the phone works with all programs.
But if i try Usb Audio Player Pro, volume don't work on the phone so i can change only with the Dac. And the Dac is good but... a lot of background noise in the volume change...
1. Don't allow your source to control the volume, it will degrade the sound and you may as well use a different dongle.
2. As @SQ13 has already said the noise and need to readjust the stepped attenuator after choosing the right "step" is a side-effect of the design.
I have no idea if other stepped attenuators have this side-effect but its totally normal for the miniature one in the DC Elite. I can't wait for a DC Elite 2 with a better stepped attenuator and 2 or 4 ROHM DAC's that will be an awesome device.