PhoenixRising & Lynx have released a new homebrew demo for the Nintendo DS with sound, heres some info :
"Looks like we are having problems going above 600k.. And, you have to give it a few seconds to load the samples prior to pressing left or right... and for some reason, it doesn't stop playing the sample.. so songs run on, and if the sample rate changes.. well, you'll hear.
But now everything should be in stereo, though it's marked mono in the user interface."