B&W DM600 speaker terminal question

I've purchased a pair of B&W DM600 S3s and want to use 4mm Banana plugs. However, I'm a bit confused (it doesn't take a lot) the speaker sockets seem to have plastic plugs wedged in them. Should the plastic plugs be prised out to accept the plug? There's nothing in the instructions and the shops now shut and I'm keen to give them a go.

Brendan