So I know this thread is about 3 years old but I am hoping someone who knows more than me will see this and help. I am trying to build this setup for my master chief helmet and followed the instructions exactly but am only getting a buzzing from the speaker. I set up the whole rig to test before putting it in the helmet and have changed out every part one by one to try to eliminate any bad parts. I adjusted the gain on the microphone amp and volume on the sound amp. I assume the microphone amp also serves as the microphone but I am not that familiar with this level of electronics so that was just an assumption. The only other thing I can think of to troubleshoot is to just soder everything up incase its a bad connection point.
Here is a list of components in case I messed that up.
and I added these to make wiring easier on my second pass.
Thanks to anyone who happens to help.