[viggen]

i prefer klei bullet plugs

[FullRangeMan]

what kind of 'audio signal' goes through that ? 

I will clear you, this is a IEC C14 power plug.
No grip, no click, no screw to fit in the amp.

[nlitworld]

Tube connectors are great imo. They fit into female tube connectors or also into binding posts. I had another amp with KLE binding posts and they worked just fine. KLE banana plugs were what I used before, but are more expensive and more finicky with no better sound.

[Archguy]

Someone more knowledgeable about connector designs would need to weigh but my assumption is the connector that maximizes contact surface area and contact stress would be better.  I’m guessing spades would be preferred for those reasons.

Mechanically I prefer spades over bananas and how the cables lay but found the amp end to favor amps with horizontal binding posts that are elevated enough above the shelf, or deep enough, to provide cable clearance.  The speaker end was also a problem for me as the binding posts on my Spatial M4s are close to the floor.  Lesson learned too late for me is straight/locking bananas for general adaptability and spades for appropriate applications.

Pretty much this.  The geometry favors spades and so do I.

However I use bananas for convenience here and there.

Never been caught up in any kind of audio purity spiral!

[FullRangeMan]

For audio service low mass connectors are preferable.
WBT RCA are hi mass connectors.
DNM RCA are low mass connectors.