2013 S60 Speaker Info

[simulacra]

Hello.

Does anyone know the size of the in-dash speakers?
i am assuming there is a pair of them in there since it is supposed to have 8 and I see 6 on the doors.

does anyone know the ohms of all the speakers?

i have found conflicting info online.

i want to add an amp and i am wondering if i need to replace all the factory speakers or if i can manage with just replacing the front component speakers.

thanks!