Strangly enough -
I have been using Memorex 4x DVD-R disks for some time
and have had very good results w/ my 812S when played on my 50" Hitachi big screen. 5.1 audio has been pristine & there been no artifacts. I just bought a stack of Ritek DVD-R silver matte which appears to be of the same quality
as I have yet to end up without even a single coaster.
Another advantage of the -R media I have seen is that it plays in every set top box I have tried it in, including a 5 yr old Sony & a 6 mth old Panasonic progressive scan.
I have not modified my unit in any way except for factory firmware.