I understand it doesn’t seem to be possible to have different volumes set for foreground and background apps on Android, but it is very difficult to hear the sensorware synth over most background tracks I’ve tried. The closed hat, ride and low velocity snare hits are lost completely, but the high velocity snare crack, open hat and toms cut through like rusty knives. Basically, it’s impossible to compete against a compressed audio track, so I’m suggesting adding the ability to adjust/compress the relative drum volumes & sensitivities in order to compensate when playing over compressed audio.
Are you using the default max volume in Sensorware. You can adjust the max volume slightly higher and the dot turns yellow. This makes volume about right for me when playing against Spotify tracks on iPhone.
Similarly with GarageBand on iPhone, when changing drum sets for some reason volume adjusts to 70-80% default and you need to adjust in settings to maximum for good balance against Spotify running in the background.