I've seen a few posts on this topic, so please accept my apologies for this sanity-check. I'm doing one of these one big instrument / all the sounds in different groups type projects. From previous posts, it seems that good practice when switching sounds, is to persist the current group, and when it changes, purge all groups out of memory, then purge 1 your current group using purge_group(). Is that all you need to do? It's what I currently do and it seems to work fine. I was worried about stuff like what happens if you've got sequencers or incoming MIDI data, will the KONTAKT engine handle that gracefully when you purge groups? It seems to, but if anyone out there knows for sure, I'll sleep better tonight Thanks!