I always thought that the Amiga's distinctive sound was because of it's poor quality basic DAC with no oversampling/interpolation like what a real audio DAC should have (such as any CD player or sound card).
I'm not knocking Paula, I like it as well, but I just assumed that was the reason.
To me Paula sounded a lot better than the Sand Blaster and Sand Blaster Pro, as I recall having those boards. I even had the original "Game Blaster" for a which which was like having 12 of the stock PC speakers going at once.
I wonder if this Paula audio emulation technology could be used to give FPGA based Amigas more accurate sound?