Get into sound settings and check what you have under Recording. if your 3DS is showing up as a microphone it might sound very loud and distorted, but if it shows up as Line In, then it should sound great. Might be a way to set to port be used as a microphone or a line in.Laptop?
I have windows, and it look like that
I will buy it, if in the worst case it won't work, it's 0.99€, nothing to lose...