We bought our son a capture box for Xmas which has a microphone input (so he can record commentary whilst playing Minecraft and other Xbox games). We've tried two microphone's and the input sound level is extremely low (even with game sounds turned off), so I'm looking for a cheap solution. The audio coming from the Xbox is fine, it's just the microphone input that's low.

Other than buying an amplifier/audio mixer, I was wondering if we could use the gaming headset and configure the Xbox so it outputs via TV. I believe this is possible in chat, but only audio from other online players is heard via TV speakers. I also have a USB microphone so could this be an option similar to a karaoke setup?