By default, BluOS players will go into a low power standby mode after 15 minutes of no playback on the device. On players with an internal amplifier, this will also put the amplifier into a standby mode after these 15 minutes. Putting the amplifier into standby helps to reduce power consumption and also improves the longevity of the amplifier by allowing it time to cool down between uses.
With amplifier standby enabled you may notice a small delay when beginning playback on your BluOS device as the amplifier is warming up. To disable this feature and allow more immediate playback on your BluOS device out of standby you can go to Settings > Player > Amplifier Standby.