One caveat - there's no really easy way to trigger them to play. You have to hold down the Play button for ~1.5 secs to start them. Taping down the button and switching the power on and off won't work, either. The Play button has to be prressed and released to begin playback. There may be an off-the-shelf controller available in the near future. I'm keeping everyone posted on the progress.
I use a Mac. The PDF instructions don't specifically say but it looks like it's just drag and drop the MP3 files (not AAC of course) onto the player on the desktop just like a regular USB flash drive (?) I have to dig up my Lightning FX unit when I go up to my parent's this weekend. All this lightning FX talk for cheap prices has got me thinking about it LOL. Last year I borrowed an RCA brand clock radio CD player and used that to trigger the Lightning FX. And you could hear the sound. I forgot this unit has an RCA Audio In plug. But the thing is if you want to hear the sound from the MP3 player then you'd have to hook up speakers (like small computer speakers for example) and not hook it directly into the RCA Audio In - right?
How difficult would it be to interrupt the audio out line from this/any MP3 player via a relay hooked up to a motion detector so that the thunder and lightning goes off when someone passes a specific spot?