asked this way, no. Audio library has only the functions you may find in the Audio System design tool https://www.pjrc.com/teensy/gui/
If you mean can you write a program that uses audio library AND SdFat, yes. See recorder.ino in Arduino path
".....\hardware\teensy\avr\libraries\Audio\examples\Recorder" for an example of using Pauls Sd wrapper of SdFat. To use Greiman's SdFat you maust change include file and adapt to Greiman's API.
Why does it require SdFat? That Sparkfun board is just wires to the socket. Should work with the SD lib.
About your original question, the Audio lib uses SD, not SdFat. If you really must use SdFat, you will need to modify or delete several files in the audio lib.
This thread doesn't seem to say which Teensy you're using. Presumably it's Teensy 3.2, since you're asking about the audio lib...
If it's a 3.3V Teensy, like 3.2 or LC, then you do not need those resistors. The signals are already 3.3V. Adding the resistors will reduce the signals too much. Especially Teensy 3.2 is *much* faster than regular Arduino, so the resistors also add too much delay as well as reducing the signals too much.
If the circuit is already built, just remove the 3.3K resistors (the ones which connect to ground), and replace the 1.8K resistors with wires.
Hello!About your original question, the Audio lib uses SD, not SdFat. If you really must use SdFat, you will need to modify or delete several files in the audio lib.