I turned my receiver on the other day with it set to the DVD input. I am using a Pioneer DV-45a with a digital coaxial cable. When I turned the DVD player (receiver was already on), my mains popped. I turned everything off and checked the coaxial connection, unplugging it and plugging it back in. I then turned everything on and the pops went away. However, if I get my ear up on the speaker, I can hear a very faint pop sound when I turn the DVD player on. I don't hear any noises like that using analogue inputs (CD player, VCR). Is it normal for there to be a very faint pop sound when turning the DVD player on?