Re headphones, in the UK both IR and RF systems were used.
If you have the Volvo "factory" system, single DVD player in the centre front arm rest then you have IR headphones.
Alt if you have a DVD multichanger under the floor in the rear, then its the Volvo UK system and it uses RF headphones.
Obviously the systems IR & RF are incompatible, so take care choosing bits and get the correct ones, a search on the forums will get you all the info you need.
Hope it helps.
