I have a Sony STR-DE475 for over a year now and been very happy with it. It is running with 5.1 surrond through various devices. I recently changed 32" LCD for a different one and noticed a high pitched feedback scream during some broadcasts, such as football, when played from a sky+ box with optical and L+R connection through the sony reciever. This is the same setup as with the previous TV but was not nocticable then. The volume on the TV is set to 0. The noise is most noticable when gaps in high volume part of the soundtrack such as gaps in spoken commentary.