Seamless transition between sounds?

I have music in my game (of course lol) that loops over and over indefinitely (unless it changes states etc). The files themselves are all fine. I have one song that loops over and over just fine using Event.SOUND_COMPLETE. I have another song that I’m trying to add which has and intro, so it’s split into 2 files, the intro and the loop part. When I try to use SOUND_COMPLETE to transition from the intro to the loop, there is a gap. But the loop part itself loops just fine. So does the other song. I am doing nothing different for any of these.

Why am I having problems with the transition only? Is there another way to do this, without having to hardcode time values and such in?