Bluetooth Headset (HS): Creative WP350 ( APT-X enabled)
sound have distorsion, when using Bluetooth connection, not all songs but especially those who has a high " level" ( volume) when ripped. this distorted sound could also happen now and then on my old Android 2.3 phone, but it was not as bad.
to me it sound like the Spotify app have slightly to high output level, and the phones bluetooth circuits cannot handle that.
the "quick fix" is to lower the output volume on the phone, and increase it on the HS.
However this does not fix the issue completely, it still leaves Spotify with a sound that is quite far from good.
using my old MP3 and the buildt in player on the phone and same headset results in exceptional good sound.
my suggestion is that maybe Spotify should look at the output level, I know that some years ago output volume on Android phones was quie weak, and Spotify boosted that a bit. however that is not the case anymore ( not with the HTC One X anyway) and if there is a need for higher volume there are apps like Volume+ that can help that.