When my amp, a Marantz PM 7200, is on for a few hours, without playing music, it will make a clicking sound, only once: there isn't another click when I put on some music. This ritual repeats every day: one click when on for a few hours. It's the same click you'll hear when you switch the amp on and/or off (the relais). Is it a faulty relay and do I have to worry about anything?