Every now and again a sound comes from my receiver that sounds almost identical to the sound I get when I turn the receiver on. Sometimes just once and it's over and sometimes it's a very rapid back-to-back-to-back sound; almost like there IS a short in it or some wires are crossed. The receiver is approx. 6 years old and in great shape, or at least I thought it was. No audio problems as far as clarity or static. All in all it's not a major problem, just kind of annoying, really. Just curious if anyone may know if it's about to die on me or what the cause may be. It must be internal because I've checked ALL incoming & outgoing connections as well as the cables themselves and they're fine. Thanks in advance for any info!