New songs start at full volume with earphones

When I'm listening to music through earphones (standard iphone earphones or 3rd party), every song starts at full volume. I'm using iphone 5, it happens with both the music app and 3rd party music apps, and happens both when I select a different track to play and when a song naturally comes to an end - whatever the volume was set at it goes back to full volume. I have both sound check and volume limit turned on (not that this seems to make any difference). The issue does not exist when listening through the inbuilt speaker.

Am I doing something stupid?!