Check your 'heavy-gauge stranded copper speaker cables'. Try something not so heavy and not so stranded. A couple runs per side of 20ish gauge insulated solid core hookup wire will knock your socks off. A practically free experiment. Or buy something a notch more expensive than what you've got, and stay away from stranded.
I wouldn't normally guess Cardas ICs would be a problem, but you might have a bad match with the ARC gear. Put some art on your walls to break up the reflections. Play around with it, but stop suspecting the hardware. It's fine.
I wouldn't normally guess Cardas ICs would be a problem, but you might have a bad match with the ARC gear. Put some art on your walls to break up the reflections. Play around with it, but stop suspecting the hardware. It's fine.