The 888 has two basic sections: an analog-to-digital converter (record input) section and a digital-to-analog (playback output) section. Each section consists of four identical stereo subsections: channels 1&2, 3&4, 5&6, and 7&8. When you first power the unit, it wakes up in "stand-alone mode" where it sends whatever it finds on its analog inputs to its AES/EBU digital outputs. You would probably hear your sound if you could monitor digital outputs 1&2 with the 888 powered on, but your computer off.When you boot the computer, the software breaks this "stand-alone mode" connection, and connects the converters to the DSP card instead. That's why you see the "levels" disappear when the computer boots. When you put a track into 'record', the DSP routes the ADC signals to the DAC, and the sound appears at the 888 outputs.