Especially the tails of the drum samples could be shortened greatly to save some space without any difference in sound.
For anything that is not an ride or cymbal sound, yeah.
I'll take the blame for that
Most of the samples are from me, so don't blame yourself. If, its my fault.
The last revision I did was mostly panning implements and it was 26.2mb at the time. 12.1mb isn't terrible compared to (at some point) 31.x mb but the SNES reconstruct is only 178kb so realistically we could probably get it down in the 2-3mb regions with no appreciable loss in quality.
If every instrument used one sample and with each drum sample being mono, then maybe.
Other then that, im updating the link. Now, its 11.3MB without any apparent quality loss.