Hi djpk,
That’s a great question one I have been wondering about. As always the definitive answer is “it depends”. Here is my experience as an audiophile and as an electrical engineer.
Audiophile experience.I am constantly reconfiguring my HiFi. Plug in banana connectors are the way to go for connecting while bending over the amp rack or reaching behind a speaker. For some time I used set screw banana connectors on Kimber Kable 8TC. My issue is set screws into stranded cable is not reliable in the long term. I believe the stranded wires can move away from the pressure point formed by the set screw and connector wall loosening over time. At first they work great than some time later the sound is a little ‘off’ or intermittent then while de-bugging the gentlest of tugs and the wires falls out of the banana connectors. After a few times listening was interrupted while I went in search of the small screwdriver to rework the set screw connections I switched those sets to WireWorld’s $2 each 10 GAUGE SET SCREW BANANAS
https://store.wireworldcable.com/products/10-gauge-set-screw-bananas-individual?variant=12463960883284 only discarding the set screws and soldering them onto the 8TC. Soldering required a temperature controlled iron that could put enough BTUs into the connector and wire mass. It was a bit tricky filling the connector’s shell with solder without it flowing onto the spring tube working end of the connector. As a segue into the next part of this note WireWorld says for $2 each one gets “10 gauge banana plug connectors come with a set screw included, no ferrule and no shell.” Ferrule is a synonym for what this thread is calling ‘crimp sleeves’.
Electrical engineering experience.
In industrial electronics the use of crimp sleeves of ferrules is common when larger gauge wires need to be field terminated to terminal blocks. The ferrules’ job is to overcome the creep phenomenon between wire and terminal blocks’ set screws by giving the set screw a single unmoving metal piece to lock into.
Too much detail here (warning, German engineering ahead complete with DIN standards):
https://www.phoenixcontact.com/online/portal/us?1dmy&urile=wcm:path:/usen/web/main/products/subcategory_pages/Tools_P-25/8180ec6c-b52b-4694-a5a6-ec0f28558052/8180ec6c-b52b-4694-a5a6-ec0f28558052On Amazon search ‘wire ferrules’ and for under $30 you can get kits with inexpensive crimp tools and an assortment of ferrules to play with. The WBT and Furutech ferrules djpk mentioned are like these I am guessing with better/known metallurgy.
For a modest 2.5x upcharge over my tricky soldering solution WireWorld sells “10 gauge set screw banana connectors. Set screw, ferrule and shell included.”
https://store.wireworldcable.com/collections/adapters-accessories/products/10-gauge-set-screw-banana?variant=1055857619. In 20/20 hindsight I should have used these, if you lack good soldering equipment and skills you certainly should.
To repurpose the famous real estate truism the three important things when doing wire crimp connections are 1 size, 2 size, and 3 size. When the wire size and ferrule or contact size and crimp tool die size are all matched the resulting crimp connection yields what we call a ‘gas tight connection’. The gas to keep out is earth’s atmosphere the oxygen of which oxidizes many metals and other pollutants likewise foul electrical conductivity. A well-made tight crimp connection at its center has the metal parts crushed together so tightly air is excluded. That is also a big part of solder’s job in soldered connections, sealing out the air. Back to this threads topic of plug in banana connectors terminated at home the ideal to strive for is crimp sleeves a.k.a. ferrules sized to the speaker wire in use that can then be screwed down tightly into the banana connector.
