Seamless audio playback?

Does anyone have suggestions how to achieve seamless audio looping with HTML5?

I have problems with the default option:

soundChannel = sound.play(0, 100);

and when stopping 1 sound and playing another 1 right after it:

soundChannel.stop();
secondSound.play();

This is even a bigger problem, as I need this second sound to complete the track (getting a ~0,5 sec gap, even when the app is running at 60fps).

I know that Howler supports audio sprites, and I think I read somewhere they are for seamless looping, but I’m not sure (and I’m not sure I can use them with OpenFL?).
Does encoding of the sounds matter (could switching from VBR to CBR help, for example)?
Can the second case be related to MP3 overhead?