F28335 and SPI interface with SD card

I am working on a project where my goal is to store data from a guitar onto an sd card and play it back on top of what the user is playing. Basically, it is a loop station guitar pedal. I am trying to use an SD card because of how cheap they are and how much memory they offer. I have audio data coming in and out of my processor and codec, and I also have TI's app note on SD interfaces with SPI. I have noticed that all of the data transfers are done in blocks of 512 bytes, and not necessarily in real time. I want to be able to run interrupts that store the data as it is received, and play that data along with incoming data. Should I be trying to use the byte transfer function, or write mulitple blocks from spraao7? Thanks for the help.