WBT Spades -- Crimping needed??

I just purchased some Canare 4S11 cable and am looking to terminate them properly. I'd like to connect the speaker end of the cable with spades (biwire), and so far I've read that WBT make the best spades.

However, it was not clear to me whether I can insert wires directly into the WBT spades or whether I need to insert a sleeve onto the wires before adding on the spades.

I have no crimping tools and am not looking forward to have to purchase any, so any help is appreciated.