Some people swear by a soldered joint. Others don't. I use either depending on what is easiest to fit to the cable type. Can't say I've heard any difference between soldered or screwed on plugs.
I've only had oxidation issues with one speaker cable and that was the old Monster Spiral type. Probably down to the level of impurities in the copper I'd guess. I still have this cable and use it occasionally though. It actually sounds decent.
It is impossible for anything digital to sound analogue, because it isn't analogue!