gapless has nothing to do with the audio files/format you use - it’s all in the players firmware.
That’s wrong. If the file format introduces a gap, which exact length cannot be told from a tag or so, no firmware in the world can remove it. And I think (almost) all compression formats do introduce such a gap, but only some of them also store the information neccessary to remove it while decoding.
There is of course another gap that comes from things done in the firmware (like waiting until the first song finishes, and only then starting to fill some buffer with data from the next one), but even if the firmware does a perfect job here there still can remain a gap because of the file formats insufficiency.
