My Logitech Z680 speakers have been working fine for around 6 months; one day they've simply refused to work. The problem is that they are powered, yet the red light doesn't appear. I've replaced two fuses - in the plug and in the main unit/subwoofer, but that didn't help. What could be the reason? I'd rather avoid expensive repair by experts - it would be the last resort.
Speakers not working 
Linear Mode
