You apparently have a Marantz 8B tube amp. You will need a preamp to connect from your music source to the Marantz. The Marantz 7 was a preamp - not capable of driving a pair of speakers!
@eltabor, There were two versions of the JBL C-50 Olympus a powered version, and a non powered version, the powered version, had a built in amp, called the energizer.
You can use "tape out" on the receiver through an rca stereo cable into the main/aux input of a preamp. Use the receiver's selector switch to choose between "AM or FM" and "phono".
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