Need help buying new speaker cable

Fix Em!

Why not do it yourself?

https://www.amazon.com/s?k=wbt+banana+plugs&gclid=EAIaIQobChMIlv6Cs9iX8wIVwAeICR1R1gMLEAAYAyAAEg...

If you send them in, you never know how 2 weeks can turn into 3 ...

You can use lamp cord, put your own connectors on while you wait, then hear the difference when they return fixed.

https://www.homedepot.com/p/Commercial-Electric-Center-Pin-Quick-Connect-Banana-Plugs-Y293035/203726...

I would recommend spade connectors over banana plugs if your amp and speakers can handle spades. 
Most banana plugs allow for spin which means there is not a solid connection. 
But you mention you aren’t able to hear differences in cables so I wonder if your system is resolving enough for this level/cost of speaker wire. 

would right angle bananas be any advantage?

https://www.amazon.com/Goaycer-Banana-Plugs-Right-Angle/dp/B08NP5R3BB/ref=sxin_13_pa_sp_search_thema...=

I used WBT locking banana plugs to alternate/compare 3 different amps, there are many to choose from, here's one for the idea

https://www.parts-express.com/Stacking-Banana-Plug-with-Dual-Set-Screws-Poly-Carbonate-Sh-091-3608?g...

As an electrical engineer, and somebody who has a pretty extensive knowledge about wiring. I see absolutely no way ’ultra expensive’ high quality oxygen free stranded wire, regardless of the amount of strands it has, will in (short lengths especially) make any difference whatsoever.

With analog cables, sheilding is extremely important so differences in quality would surely effect the noise floor...

Please, somebody show me proof as to how this phenomenon of higher fidelity will be the result of me spending thousands on several meters of cable. Just because I don’t see how it’s possible doesn’t mean it isn’t, but none of my professors at RPI would jump on this bandwagon.

Making use of The Cable Company's inventory of used cables is the most practical way to find what works best in your setup. If you can't hear a difference in sound then just worry about how well they are constructed. Good luck.