Report "USB and bought a set of speakers Sony SS-B3000 Bookshelf Speakers with 8-Inch Woofer to install to the system but the Crosley has only one pair of audio out RCA outlet. Radio Shack told me I need an amplifier (with a pre-amplifier) to connect between the Crosley system and the speakers. Can you let me know if this is correct and what kind of amplifier and other connecting cables will I need? The Sony speakers' cables are not RCA. Thanks, Berta"