Internal SD Memory
The BR-800 has the ability to record 4 tracks simultaneously onto the installed SD memory card. This will be audio coming from inputs 1 through 4 on the back panel such as microphones, keyboards, drum machines, etc.
USB Functionality
When using the BR-800 as an audio interface or control surface, all incoming audio connected to inputs 1 through 4 is mixed together and is seen as a single stereo audio signal in recording software--the BR-800 will be seen as "L/BR-800" and "R/BR-800" in software.