Bananas rule, spades drool. End of discussion.

I use one-piece BFA style banana plugs (not really banana plug but fit into the same female connection).  They fit tight, stay tight, and are one piece.  Tranditional banana plugs are a challenge because they have to be either gold coated steel (try a magnet on the cheaper ones) or they are solft and can loosen up.  They are also multiple pieces and I've had them pull apart on my.  

Spades, in addition to what has been said, can sometimes be pulled sideways into a short.  

BFA rules.

Jerry

Well, I usually don’t use any connectors for speaker cables, just some teflon tubing to make a diy 47labs style plug.

Granted, that works for me mainly because I’m using small-ish gauge solid core wires.

For convenience, I sometimes use these hollow BFA bananas; they fit very tightly, are very low mass, have a larger surface area than spades connecting to the socket, and - my spades tend to come loose in my (limited) experience .

They also are very affordable, and I have yet to break one or fail in any way.

I’d love to some day figure out what thread speaker terminals most commonly use for the outer part that holds the spades/cables in place, to use a simple copper nut instead of the usual plastic clad brass things .

My speakers and the amp use a thread that almost is a metric M6, but a tad larger than 6mm; so it's probably an imperial thread size of unknown pitch.

Any hints for an ignorant European? 😉

All Jeff Rowland amps use Cardas clamp for spades (or bare wires).  It does not accept bananas.  It creates extremely strong connection and rotating spade won't make it loose.   I have small Rowland 102 with speaker connector and it is great (other than not accepting bananas).

If you biwire with two separate identical cables, which is the recommendation,  and you only have one pair of speaker outputs on your amp, well then you have no choice but to use spades on one of the pairs (amp end). 

I’ll chime in with a comment on this topic.  I had spades for many years and I think one of the two cables would come loose and drop off every couple of years.  It didn’t occur to me that I could use channel locks to tighten them so they wouldn’t fall off.  Finally I discovered that there are different sizes for spades!  At that point I examined mine and they were clearly too big for my binding posts.  That was clearly the reason they would fall off.  So I finally switched to locking bananas.  That brought up another problem.  For some reason I struggle to open them and I’ve actually come to dislike them.  I’ve read that regular bananas  can loosen but I have them on my electrostatic speakers and they’ve never seemed loose.  And I’ve had the same bananas for decades.  So I prefer regular bananas.