Here's a quick rundown of what the routing is for the audio tests.IntL Internal loopback of all analog & digital I/O channels (i.e. input 1 to output 1, input 2 to output 2, etc)Sgnl Generates a 440Hz sine wave on all analog and digital outputs. (adjustable from 0dB to -42dB).SpIn - 1/2 SPDIF input to DAC channels 1/2SpIn - 3/4 SPDIF input to DAC channels 3/4SpIn - 5/6 SPDIF input to DAC channels 5/6SpIn -7/8 SPDIF input to DAC channels 7/8SpIn - All SPDIF input to all output pairsSpOt - 1/2 ADC channels 1/2 to SPDIF outputSpOt - 3/4 ADC channels 3/4 to SPDIF outputSpOt - 5/6 ADC channels 5/6 to SPDIF outputSpOt - 7/8 ADC channels 7/8 to SPDIF outputSpAg Simultaneously routes ADC channels 1/2 to the SPDIF output & the SPDIF input to DAC channels 1/2Adat Simultaneously routes ADC channels 1~8 to the ADAT optical output.& the ADAT optical input to DAC channels 1~8Note that the audio tests default to working at 44.1KHz (the default for Standalone mode) if set to Internal clock under the Utility->Prefs page, so all 18 I/O channels are functional