@ustk You want to morph between IRs. This won't model non-linear systems well, though. One way to do that is with many convolution engines in parallel, each processing an individual overtone. All that aside, the quality of your sounds is the most important characteristic of the system, and until you've optimized that (if possible), there's no need to get exotic. If someone who really knows the ScriptNode side of things wants to answer some questions for me, I'll help you with whatever whacky stuff you'd like to do with impulse responses. (I'm a longtime MAX/MSP guy; just don't know the HISE-specific implementation aspects.) My $0.02 is that HISE is not the place for fancy IR stuff, and if we ask anything of @Chris, it would be to document and fix what's already there, not add anything new (not that he has a responsibility to do either). Just my $0.02.

@Christoph-Hart Thank you for the kind words. I thought so, as well about the permission – I tried the Documents and Downloads folder – on both cases, the OS asked permission and I granted it. Same result, tho. I'll try some other permutations. I've also amended my original post to see if someone can try this under Windows or GNU/Linux, where I suspect it might work fine.