Someone attempted to do a gamerip of Sonic Rush Adventure with the second method you mentioned. It didn’t work out very well. (I should know, I talked to THAT individual about that at Gamingforce.)
However, if you were to direct me to resources for the second method, I would try it out just for fun. (Who knows? I may actually like it.)
NitroExplorer: http://treeki.googlepages.com/nitroexplorer1.2.zip
VGMTrans: http://www.vgmtrans.com/
As far as recording with a USB cable, if it is something like a male audio connector to USB cable, I could possibly see it working, but I don’t know if they make those (You may have to solder one yourself).
The DS doesn’t even have a USB port. (That port at the back that you plug your adapter in to? Do NOT force a normal Type-B USB cable into that!- you not only damage the DS, but it also wouldn’t fit).
I actually have a NDSLite USB charger >_>
Could someone please upload VGMtrans, because the website is down.
Thank you very much.