So I recently received all (of what I thought) I needed for recording vocals. I received:
1. an MXL 770 Condenser Mic
2. a Nady Audio SMPS-1X 48v Phantom Power
3. A boom stand for the mic
4. a XLR M-F chord
5. a XLR F-USB chord.

I have the set up as follows:

MXL 770>XLR M-F>Nady 48v Phantom Power>XLR F-USB

I am currently using GarageBand, and have switched the audio input to the PnP USB Sound Device setting. Why is my microphone not picking up sound? I HAVE TURNED ON THE PHANTOM POWER (and plugged it in). Anyone have any help?
I don't know much about that setup, but it looks like there might be drivers for the PnP. Do you have the latest drivers?
Did you select your input source in Garageband? It is probably looking for sound at your I/O and not your USB device.
"Your sound is in your hands as much as anything. It's the way you pick, and the way you hold the guitar, more than it is the amp or the guitar you use." -- Stevie Ray Vaughan

"Anybody can play. The note is only 20 percent. The attitude of the motherfucker who plays it is 80 percent." -- Miles Davis

Guthrie on tone: https://www.youtube.com/watch?v=zmohdG9lLqY