I found my Mike actually does work, but as VaidTalon said, it's pretty useless. I have to shout with my face up against the screen to be heard at all.
I still haven't found the +20dB boost that was mentioned though?
My first computer:
Microdrive (continous tape loop that stretched and gained capacity the more you used it)
ZXPrinter (sparks vaporized aluminum paper)
Cassette Interface for storing programs at, I think, 2400 baud.
Color TV output!
"Dead Flesh" feel keyboard.