Let's just speak about *SmoothStream* feature offer: fading to pause, fading to stop, fading in the beginning (it's a function of volume - not very hard to create). How do you evaluate it?
Fade to pause/stop is already on the list of suggestions, I'll add faded start to that. Could you try WASAPI and tell us what soundcard you use?
What I think is going on is that your soundcard(or drivers) are giving you a little distortion when sound inits. The only way to fix that is to keep the sound stream "alive" at all times. that shouldnt' be too hard to add.
That's a workaround, not a fix. It also doesn't work when the sample rate of the output changes, because that requires re-initializing the device.
1. WASAPI - still presents, but less loud and noticeable. Again,
it doesn't happen when song/music already faded in the beginning.2. I know that i wanted to upload example track, but since our music society already wished stop/pause fading, i feel that not only me was bothered with something happening in the sound.

3. WHy there's still no commercial version of XMPlay with minor cosmetic and functional improvements for dollar or two? You guys should think twice now before you update versions, because you are closer to ideal than plenty of other player's creators.
