I have gone through some of the forum and found a lot of discussion when DMAChannel.h was being written. Those examples I've found seem to be about copying memory from one array to another. I'm not clear, though, on how DMAChannel.h can be used to perform transfer from the ADC to memory. I'm also assuming that this is a relevant thing to do - thinking about it a bit I am not sure if it's any better than just reading the ADC using analogRead.