camillo jr wrote:I'm getting several mysterious .aiff files (...) I'd like to get rid of them, just to reduce the clutter in that folder. Can I safely delete them all after I quit Logic?
Those are fade files. They are necessary to playback your project, however you can safely delete them at any time, even while your project is open if you want. Let me explain:
When you draw a fade in the Arrange area, the next time you press play, Logic quickly bounces that fade as an audio file, and puts it in one of those fade files. Depending on the number and size of those fades, this can take anywhere from a negligible amount of time (a few ms) to a long, long time (several minutes). Once the fade file is created, upon subsequent playbacks Logic uses them and can start playback immediately.
If you delete the fade file, then the next time you press play, Logic will look at the fades in the Arrange area and re-create the fade file, which again will take a certain amount of time.
Whether you decide to delete those fade files or keep them on your hard drive is entirely up to you. If they don't bother you, I would say don't touch them. If you want to clean up your hard drive and have a smaller project size, you can safely delete them. Your choice.