Getting 4K with Classe SSP-800

Just use the TV inputs for your video sources and you will have full resolution.  Run the Audio through the SSP-800 with HDMI eARC from TV and it will send the sound no matter what video source to the Audio Processor.  I had this Classe SSP-880 and ran it this way with no issues.  If you have issues with HDMI eARC (Audio Return Channel) you can also run Optical out of TV into the SSP-800.  

Run your sources into the preamp in 1080p. 80% of people can't tell the difference between 1080p and 4k, also when you stream 4k content you aren't getting that resolution nor HD audio because its compressed. 

On a side note, your SSP and the Anthem D2V are still ones at the top best sounding surround preamps. When you replace it, take a look at the Anthem AVM 90. In my opinion it bests yours and the D2V but not by a wide margin. The AVM 70 would be a lateral move sonically but get you all the newest technology. 

Your TV will automatically upsample any 1080p content, so there's no benefit to relying on the TV for video processing. Avoid using Optical or eARC for audio—both are bandwidth-limited and won't deliver full-resolution formats like Dolby TrueHD or DTS-HD Master Audio from Blu-ray discs. While eARC has higher bandwidth than ARC (up to ~37 Mbps vs. ~1 Mbps), it's still insufficient for full bitstreaming of advanced codecs, and the SSP-800 does not support ARC or eARC input natively.

Instead, use an HDMI audio extractor to separate the audio from a 4K signal and send it to your SSP-800 via HDMI, I recommend the HDFury Vertex²—it's a highly flexible HDMI matrix and splitter that can strip audio cleanly and pass full 4K HDR video to your display while routing high-resolution audio to your processor. I used one with my SSP-800, an HDFury Vertex 2nd, and it worked flawlessly.