I have used piano samples in a synth app using the Juce Synthesiser. It works great on the Mac. It works on other platforms too but I get distortion when I play several notes (voices) simultaneously. I am assuming this is due to lack of audio compression in the Juce synth when adding voices. I can understand why you (Jules) didn't bother adding a compression algorithm , but I found it weird that it works (no distortion) in the Mac application. I didn't see anything specific to the Mac. Or am i missing something ?
Sidenote: I fixed the problem by modifying the gain in SamplerVoice::startNote, but I am not sure this the right way to do it (I don't want to lower sample volumes either as I would lose dynamics).
lgain = velocity/5; rgain = velocity/5;