The Loudness On equalizer setting on your Phoenix Android Radio auto head unit should only be used in rare circumstances. Some users are reporting severe speaker damage and in many of these cases, blown subwoofers. Turning on Loudness drastically amplifies your stereo and will throw your subwoofer out of range. You may begin noticing your car subwoofer to rattle on heavy bass driven sounds. If you notice rattling, immediately disable the Loudness setting and check to make sure your speaker has not blown.
To avoid the Loudness setting, make sure your OEM stereo is properly turned up to an adequate volume before disconnecting it. The Phoenix Android Radio units require the volume on the OEM unit to be turned up mid-to-high. You should test different volume ranges with the Phoenix Android Radio before fully disconnecting your OEM stereo.