I would say they probably used something similar to the NCJ5FI-H.
There is no correct way to connect an unbalanced signal into a balanced input (without something to create the inverted signal). If you don't want to use the adapters, have an RCA to 1/4" mono phono cable made up.
The 'N' jacks are for use with things like headphones. Where inserting something into the jack breaks (or switches) the connection. When there is no plug in the jack the T and TN are connected so the jack can be placed before an internal amp. Inserting the plug opens the switch so the signal goes stops at the jack.
Pioneer VSX-1018AH-K, PDP-5020FD, DV-79AVi
Axiom M22s, VP150, QS8s
Sony PS3, surround backs