As the title would suggest, I have a pair of Sennheiser CX300s. The other day when I went to use them the left one is about 1 third quieter than the right, not enough to be totally unlistenable but enough to be very annoying. Is there a simple way to fix these or what could the problem be even ? They only cost me $30 so O'll probly have to just keep them as my cycling headphones as they keep the sound out well and I only keep one in at a time.