Mr.- I have the craptastic logitech "X5bla" system on my desktop and
I can't even listen to MP3 files on them unless I have the volume
turned down slightly and causes the amp to distort. So your softsynth
is probably too loud. But anyhow, all distortions have their own
characters. What you're hearing is a harsh and defined digital
clipping sound of information being out of range, since CDs play ok
your amp is probably fine. When an amp distorts it will usually sound
smoother, less clicky than digital clipping. When your speaker is
cooked it will usually sound bad around specific energies of sound(?)
like, bass will sound terrible and mids sound slightly airy / fuzzy at
low volume and then as it gets lowder it all starts to sound like a
flag in the wind.