From the T92USB manual:
PHONO/LINE SWITCH - Switches the output to either phono or line level. Use the PHONO setting when plugging into a PHONO input on a receiver or DJ mixer. Use LINE position when connecting to a line level input such as CD or VCR on a receiver.
WARNING Never connect a line level output (LINE position) to a PHONO input on a receiver or DJ mixer.
PHONO/LINE SWITCH - Switches the output to either phono or line level. Use the PHONO setting when plugging into a PHONO input on a receiver or DJ mixer. Use LINE position when connecting to a line level input such as CD or VCR on a receiver.
WARNING Never connect a line level output (LINE position) to a PHONO input on a receiver or DJ mixer.