Recording audio:
Equipment:
3.5 mm male to male audio cable,
here is an example on Amazon that you should look for as they can be found in most stores that sell electronics.
Microphone or headset, I personally use a Logitech G930 headset, but any head set with a microphone or a standalone microphone should work.
To listen to audio from the 3DS over the Line In jack over your computer speakers, try
this:
1. Connect the audio device to your computer through the line in jack.
2. Click Start, click Control Panel, click Hardware and Sound, and then
click Sound.
3. Click the Recording tab (if it is not already selected), and then click
the line in in the list of recording devices.
4. Click Properties.
5. In the Line In Properties dialog box, click the Listen tab, and then
click the Listen to this device option.
Recording gameplay:
Programs:
I use a conjunction of XSplit and Fraps to record gameplay, Setting up background and 3DS screens in XSplit and then recording the preview window with Fraps.
You can download XSplit with limited features on their site,
http://www.xsplit.com.
Fraps though costs $37 on their site,
http://www.fraps.com.
Fraps records all of the audio coming from the microphone and 3DS.
There is other screen capturing software, but this is my personal preference of doing things.
If you need any more help or just clarification I would more than welcome to help.