technically its balanced, as the earth isnt connected to ground / shield, and other things too
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however to make use of that you would need to be supplying a balanced signal to the amps . if you dont supply a balanced or clean signal you may get an earth loop, so as they say there you will need to isolate it
just googled this its for home studio but might help explain things a bit better
http://www.tweakheadz.com/all_about_cables.htm