I just sold a boss RV-2 on ebay (Reverb) and the guy is talking about a hum that he gets at high gain settings. However, I have noticed that Boss pedals always leave a hiss or something in your signal. He is now unhappy about the pedal, and I certainly did not mean to sell him something that he wouldn't like. And he got it for less than half of the new price. The hum is a faint ringing hum that you can only hear if using a considerable amount of gain and moderate volume or higher. What are your thoughts? Isn't this normal for boss pedals?? My flanger does something very similar. What should I do?