I second the comments by Kal, Kijanki, Rdavwhitaker, and others that a balanced interface can sometimes provide significant sonic benefit regardless of whether the components are internally balanced or not.
In addition to the reasons they mentioned, I would add that a balanced interface will provide considerably reduced susceptibility to ground-loop issues, and also will reduce sensitivity to cable effects and differences (particularly if the output impedance of the component driving the cable is low).
Ground-loop issues, btw, do not just involve hum problems. They can also result in an increased amount of low-level high frequency noise, resulting in degradation of "background blackness."
Does all of this mean that using balanced interfaces between components that are not internally balanced is generally preferable? Of course not. It is dependent on the quality of the implementation in the particular components, numerous unpredictable system-dependent variables, and overall system synergy.
But as I see it, it all clearly means that a blanket claim that using balanced interfaces between components that are not internally balanced will necessarily result in little or no benefit is incorrect.
It's ironic that listening experience here is being used to deny the possibility of significant sonic benefit, while science is being used to advocate that possibility. Usually it is the reverse that seems to occur.
Regards,
-- Al
