I have a new Pioneer SC-LX502 and a C61K (Sony 940 4k TV) and its flickering (Intermittent Black Screen Flash). On DIRECTV website people have called support and found that it’s a problem with the C61K receiver. Connecting the C61K to the 4k TV solves the problem sometimes. I had a Yamaha receiver that supported 4k, but not with C61K. The C61K would only do 1080P while connected to the Yamaha receiver on channels 104 and 106. Before upgrading to the new Pioneer SC-LX502 I did not have this problem. It is possible it is a HDPC 2.2 copy protection problem. I have upgraded to Monsters Ultra 4K HDMI cables that have 21 GB cable version. I’ve tried about everything I could do with the SC-LX502. My understanding DENON and PIONEER 4K receivers are having problems like this. I will connect it directly to the TV and use OPTICAL until it is fixed.