i have Logitech SPEAKER SYSTEM Z523 http/ with faulty power switch/speakers volume potentiometer. When I turn power/volume, power light just blinks for moment and then turns off having no sound. When I return volume control back to the point of powering off, minimum volume, it start blinking again. I opened speaker and plan to spray a little with wd40 tomorow when I get it, but i think potentiometer died, so i will replace speakers and keep subwoofer. My Logitech speakers have volume and bass control but my subwoofer has no controls at all, I control it via speakers. All desktop speakers only have volume control or they are too expensive (they have built in bass). How to control my subwoofer with regular desktop speakers? I need buying advice. I could buy from here http/ for 20$ but I need something universal.