My two cents on spades ending for speaker cables:
They tend to get lose after some time. A continuous maintenance of
fastening the binding posts is required. Banana plugs are way better.
For those who try to implement a thick cable (4 gauge or thicker), the
spades that can fit the cable are too large to fit the binding posts. You may
lose on that contact between the spade and the binding post some of what you
gain from a thicker cable.
For me, if an amp or speaker is not fitted for a banana plug, I'll would
avoid it!