Can anyone have any idea for the price for SL3 panles? I mean a pair.Are they still available with ML? Is it better to change the panels in pair? I am noticing that in a humid weather condition (central aircoditioned appartment), one of the channel reproduce less high frequency and becomes ok after a hair drying blowing process followed by a heavy blowing. What is the longivity of the panels in a smoke free atmosphere. I could see small black dots on each of the small holes?