Hey thanks a lot for the responses and the welcome!
In answer to your questions - yes I did verify that the blue yeti is taking the input not the onboard mic, I had thought it might be that as well, initially. I did verify that the Mac's input level under System Preferences is maxed as well...
I'm new to digital recording so it might just be me...
I bought a Blue Yeti to use with my MacBook, and the recording volume level always seems low. When I first got it I only had Garage Band, and I noticed the input levels low there but didn't worry much about it.
But then I got more serious...