Can bananas fit in tube connector? My struggle with tube connectors is compatibility. That's my reason for not using them so far.
Yes, banana plugs will fit in tube connectors, locking banana's would be better. You sacrifice some of the performance benefits though. The opposite is not always true. I have found the male tube connectors are often too large to fit into a banana jack.
I set my speaker cables up with male tube connector studs on the speaker end to mate with the female tube connector on the speaker and locking banana plugs on the amplifier end. These speaker cables will only work with speakers that have tube connectors but then, that is what I am using them with.
The male studs are available separately so it is not difficult or expensive to retrofit existing speaker cables to work with tube connectors.