A-L - most differential signaling uses a ground, just to insure that the source and destination ground potentials are close, including firewire. The problem with most of these is that the common-mode noise rejection provided by the receiver chips is not stellar. Therefore, it is still an issue. Its not that USB is inferior, just that most receiver chips are not great designs. Some are worse than others. Case in point is the XMOS chipset, which uses a really poor receiver chip IMO. Very sensitive to cables.
Steve N.
Empirical Audio
Steve N.
Steve N.
Empirical Audio
Steve N.