Can you dispense with the adaptor and tightly screw part of your spades (i.e. 1/2) onto the the B&W posts? I think that'll be better than adding another connection to the conductor chain... Had a similar case with bearlabs (cardas spades) and jm lab speakers. Ended up wedging the bearlabs spades into the larger diametre WBT posts on the JMs -- and screwing tightly.
A compromise, nevertheless...
A compromise, nevertheless...