Cana anyone recommend a plastic wrench that doesn'e scratch the metal?

This is why I think Furutech torque guard binding posts are the Best available. Impossible to over tighten, and silly easy to tighten properly. No tools required 

@zavato agree but seems an overkill solution to change the binding post completely for not wanting to scratch it lol

I get that but just commenting that they really are that good 

@zavato I agree with you though... speaker/amp manufactures should consider definitely consider thus option.

GOT IT!

Check out Knipex, German manufacturer of  (?) toolifile  tools for freak tool users. I got a beautifully German pair of channel-locks that came with a pair of synthetic “dentures” that snap onto the jaws. I use it to hold gold-plated connectors while doing the real torqueing from behind the face/back plate. I think they were about $25.
We’re audiophiles, man, we don’t need no stinkin’ cheap tools!