I am particularly happy with some of the acoustic guitar IRs floating around that are designed to use with a Fishman peizo pickup equipped acoustic. Here are a couple of sites where I found a few keepers:
Unfortunately the nature of these things is that each guitar is going to sound different thru the same IR, so no real way for me to point to the “good ones” since they might not be so good with your guitar.
That said, the keepers I found are pretty friggin amazing with my guitar. I don’t think paid or DIY options would get any better. And being able to make a D28 sound like an OM when needed is really nice.
I bought a Takamine Jasmine used and mounted a $24 JoYo acoustic preamp (under saddle piezo) just to play with a trial of Nembrini’s Acoustic Voice. It was just to test for recording (wanted to get the Gibson J200 sound). I’ll try these IR’s.
I gave my $9.99 Sweetwater special Behringer interface, a copy of Cantabile Lite, the Melda and Kilohearts freebie plugins, ASIO4ALL and selected six of these freebie acoustic guitar IRs for a friend to use with his old laptop. I put together a plugin chain in Cantabile and saved it as song file for him and it sounds just fantastic for playing his guitar through. Totally hangs with the better commercial processer box solutions though it isn’t nearly so pretty to look at. Just amazes me what is out there for free and dirt cheap.