Google Nexus 6 (Android 5.1)
Google Nexus 7 2013 Wi-Fi (Android 4.4.4)

Dark theme looks nice!

The playback controls do show up in the notifications, but do not show up when on the lock screen.
There also should be a more convenient way to remove the notification entry when the app will not be used for quite a while.

Would also be nice to be able to hide any unused DSPs, not just reorder them.