Ah, well thanks for the explanation
Now to answer Eiyeron's question properly, no
My player only supports "simple" notes, with constant amplitude (gets to its maximum as soon as you start playing it, stops playing as soon as you stop playing it (no joke !)).

Full ADSR is nearly impossible to pull off with Pulse Interleaving (which is most likely the synthesis method used here).
You could, however, support at least 2 different volume levels by allocating non-equal time slots to the channels. The difference needs to be pretty pronounced though, because the human ear perceives volumes in a logarithmic way. So, just talking about 2 channels, distribute timing so it spends approx. 2 thirds on the first channel and 1 third on the second one, and you get a decent volume difference, good enough for creating nice echos and similar effects.
Hope that explanation wasn't too convoluted...

ed: Check this track of mine, about 55 seconds in. This is a 3-channel pulse interleaving engine with pwm support and 3 different volume levels. 1st channel frame is about half as long as the 2nd one, which is in turn half as long as the 3rd channel frame.