USB audio disconnects upon sleep

Tried all USB dac audio players out there. Hibymusic is best but USB dac disconnects upon sleep / inactivity. I tried wakelock apps otg lock etc. none of it works . I think it's padfone s / x specific firmware app:battery power management within issue. As my other Android phone don't have this issue. Been on padfone x KitKat . then converted to latest padfone s firmware lollipop it still disconnects
Audio Upon sleep.