jobel the only solution I have found is to use "effects" instead of music for playing songs.. this means basically that music will loop seamlessly.. i think the only trade off is that the music is uncompressed so it might add some size to your game.. so keep your songs short.
I don't know about a giant gap, but yea if you want smooth looping music import the music as a sound effect not as "music" and it should be fine.
if you need to start / stop music it gets trickier.. but for my last game http://www.kongregate.com/games/part12s ... video-game i actually (because it was slowing me down) just played both songs all the time and simply control volume of both turning down the audio on one as i turn up the audio on the other.. not ideal, but it gets the job done.
that reads it into memory though...
I read a work around somewhere that seemed to do the trick... play music NOT LOOPED then make a Trigger on tag finished, then start the track again. Basically manually looping... so far so good..