speaker connections?

Spades usually are best as they provide for a more secure connection (You are less likely to have one cable pop off, touch the other cable, and short out) and there is less potential for corrosion. Bananas are great for convienience. As long as the metal surfaces of either bananas or spades remain uncorroded I can't hear a sonic difference.

I like spades under binding posts, TIGHT. That way the nut deforms slightly the spade, forming a gas-tight seal. Seems better to me than the sometimes-flaky bananas.
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My banana connections are so tight, I can hardly get them in the holes. You will just have to try yours and see which you feel better having. Some speakers have plastic connectors you can't tighten very much.