FYI - those three outputs You are using are all RCA OUTPUTs. Front, Rear, Substage (see pic).
You do not plug a source into this deck unless You have the proper equip
Per Pioneers support webite:
[left]
Using the AUX source [/left]
[left]An IP-BUS-RCA Interconnector such as the
CD-RB20 or CD-RB10 (sold separately) lets you
connect this unit to auxiliary equipment featuring
RCA output. For more details, refer to the
IP-BUS-RCA Interconnector owner‘s manual.
[/left]
Pioneer loves their proprietary gear my friend.