Hi, I bought a Rotel RA 931 on ebay, which when I got it home and hooked it up to my main system worked fine......gave a very dull thump when I turned the power off.....but that was it. I have now hooked it up to my bedroom system and now the speakers pop when I turn the power on.....as well as the dull thump at power off. The difference in speakers is that the bedroom ones are older KEF C20s rated 90db/8ohm as opposed to KEF Q55s rated 91db/6ohm. Could it be that the more sensitive C20s are picking up the pop....or could it be the cables that I am using? Using QED silver aniversary in the living room versus Cabletalk 3.1 stuff in the bedroom.....most also confess to a little bit of cable splicing to make a longer run out of two pieces....could this also be an issue? I did have a search but did not find anything that completely fitted with my issue. Ben Ben