I'm a proud owner of a stock R4, and I absolutely love it, but I seriously wonder if this is the right tool for your needs. I think it's self-noise might be too loud for what you need. You'd be able to run mic-in (for music many folks have to run line-in), so that will help, but depending on how much gain you'll have to add, this might not be your best choice for ambient/nature recording. Also, this unit isn't the smallest field recorder, so if size is a consideration, you might want to go for something else. Do you really need 4-channels?