Hi Jim and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, are the speakers/wires directly connected to the CDX-C5750? ...or is there an add-on/external amplifier?
I understand and bear with us; re-confirm and post back with the complete model number of the amplifier.
After re-checking wiring to the CDX-C5750 particularly the blue/white, can you please check if the external amplifier is receiving power and if it is remotely triggered by the Sony?
The "whirring noise" would appear to be mechanical and possibly be the CD mechanism. On the other hand, the amplifier is electronic and at most would produce a thump on the speakers.
Yes please; post an update when able.
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