Embarassing electrical question

Hi
Considering that i always hated physics in school i have this silly question, but first let me explain.While upgrading female RCAs on my cd player to WBT Nextgens,i encountered a wiring configuration where a positive wire was soldered to a connector and the ground was connected via a figure 8 washer to both female rcas.Nexgen being a plastic body i figured i cannot replicate the same thing so i called WBT for an advice.I was told that i can connect the ground by the way of soldering any cheap wire that i can find in my house and that it would in no way affect the sound.My question is:does it work the same way for the speakers in a way that i can upgrade only the positive binding post and leave the other one untouched?Please,explain.