Naim nac 552 questions

Hello,have acquired a Naim nac552 hooked it up works fine, has 2 rca inputs ch8 and ch9
ch 8 works fine when I press tape input on the unit, cant get ch 9 to work, do both work at the same time or is one or the other ? I have had and have other Naim units.

Have cd player into #2 works fine, I have read the manual cant really makes heads or tails of it, any shortcuts to see if all is well etc, thanks, for any input.

Thanks, I saw that in the manual, its alot of word salad to me, what I am afraid of is hitting a button/key and disengaging the rca input that is working. I also have a Naim 282 would that remote work on the 552 to change inputs etc