iPhone 5 Lightning to 30-pin adaptor won’t work with some existing accessories (false alarm)24
And that’s worth stressing - the adaptor doesn’t transport analog signal so accessories requiring that analog signal won’t work. Now, it turns out that most audio devices require exactly that, the analog output, and that’s why it’s possible that if you want to use your audio equipment with the new iPhone 5 and the adaptor you might not be able to.
The best thing to do would be to just try it if possible or check with the manufacturer of your accessories whether those particular gadgets will work with the adaptor.
source: What Hi-Fi