Do pure copper banana plugs make a difference in the quality of the speaker sound.

Minimum mass copper or brass crocodile bananas, crimped, not soldered. And to make them connect: Acoustic Revive ECI-50.
Truly secret sauce territory for connectivity.

https://www.dienadel.de/en/acoustic-revive-eci-50-highend-contact-spray-50ml/a-353635163

https://compassaudio.co.uk/product/bfa-banana-plugs-beryllium-copper-gold-plated-z-type-connectors/

The Acoustic Revive stuff is outstanding: treat all contacts incl. fuses and you’ll find it one of the best value or money tweaks anywhere.

Otherwise Chris Venhaus at vhaudio.com can probably help

@nonoise

this is why I suggest low mass, crimped banana connectors with Acoustic Revive contact enhancer. Replicating the force of crimping is near impossible on any normal binding post on bare wire and increasing connectivity of the imperfect banana surface is mandatory. On bare multi-strand wire the likelyhood of breaking wires is high, surface contact is low. On single strand wire chances are that in a bare connection the contact surface is even lower. Soldering adds resistance, no matter how good the solder.

Great reference article, btw