Table schema:
CREATE TABLE table_name_71 (digital_analog_signal VARCHAR, available_interface VARCHAR, retail_name VARCHAR)

Question: What is the Digital/analog signal with an Available interface with pci express, with Retail name with all-in-wonder x600 pro?
SQL: SELECT digital_analog_signal FROM table_name_71 WHERE available_interface = "pci express" AND retail_name = "all-in-wonder x600 pro"