Regarding the significance of how pin 1 is wired, I don't find it surprising that it can make a difference, although I would expect the magnitude and character of that difference to be dependent on the designs of the particular components that are involved.
Inter-chassis noise currents will inevitably flow through the pin 1 connection to some degree, due to ground loop and other effects. The magnitude and frequency characteristics of that noise will vary as a function of the resistance and inductance of the wiring that is connected between pin 1 of the two connectors. Depending on whether each of the two components connects pin 1 to its internal signal ground (which would be improper, but is often done nevertheless), or to chassis, or to chassis and then to signal ground through some impedance, some fraction of that noise current will inevitably find its way into audio circuitry, where it may intermodulate with or otherwise affect the audio signal.
Regards,
-- Al
Inter-chassis noise currents will inevitably flow through the pin 1 connection to some degree, due to ground loop and other effects. The magnitude and frequency characteristics of that noise will vary as a function of the resistance and inductance of the wiring that is connected between pin 1 of the two connectors. Depending on whether each of the two components connects pin 1 to its internal signal ground (which would be improper, but is often done nevertheless), or to chassis, or to chassis and then to signal ground through some impedance, some fraction of that noise current will inevitably find its way into audio circuitry, where it may intermodulate with or otherwise affect the audio signal.
Regards,
-- Al