On a scale of one to ten how would you rate.......

See the first page or two of this paper for an explanation of one of the fundamental disadvantages of unbalanced interconnections. He refers to this as "common impedance coupling" of inter-chassis noise currents with signal return currents, caused by the fact that both currents flow in common through the shields of unbalanced interconnects.

http://www.jensen-transformers.com/an/an004.pdf

Of course, whether or not this is significant will vary depending on the system, and also on the ac power distribution scheme.

Note that he refers to high frequency "buzz" as well as low frequency hum, which may correlate with the subjective perception of background "blackness."

Happy holidays!!

-- Al

Keep in mind, though, that if common impedance coupling is not a problem in a particular setup, AND if the components are not "fully balanced" (i.e., they are unbalanced internally and only balanced at their interfaces), a balanced interface could actually sound worse than an unbalanced one. That is because of the possible sonic effects of the extra stage that is introduced into the signal path to convert from unbalanced to balanced, or vice versa.

Regards,
-- Al