I think I finally have the perfect setup for my 665
After having my 665 for months of tweaking, firmware updating, switching sources, etc. etc. I think I've finally hit on the combination of equipment that I'm really thrilled with for this projector: The Panasonic DMP-UB900 player, and a Stewart Filmscreen Cima with the 1.3 gain Neve material.
I own the Samsung K8500, and it works well with my 4K LG OLED 65". At best it can send a good image to the 665, with a LOT of tweaking and compromising. For a month I owned the Philips 4K player. It looked great with the 665, but was painfully slow and had only one picture mode, so I couldn't have different settings for blu-rays and UHD discs. I kept another blu-ray player attached just for standard blu-rays. It did play the Masciola HDR test patterns in the .TS format, which helped in calibration a lot. With the Philips I was able to get the picture out to the screen perfect, but I'll get to the screen in a minute.
As others have stated here, the Panasonic works very well with the 665. I honestly didn't notice a difference in 4K picture quality moving from the Philips to the Panasonic. It appears to have the same processing engine as the Philips, and a lot of the menu options are quite similar (including the odd choice of all sliders going to "12"). The info display as a movie is playing is also identical. It still needs the contrast turned up, but colors look natural and with the HDR test patterns on Sony 4K discs it can be pretty easily calibrated along with the 665s menus for great black levels and and a nice bright average picture level in HDR. Unfortunately although the manual says it will play the .TS file format, it doesn't. But the menus are good, if not as nice as the Samsungs. The backlit remote puts both the Philips and Panasonic's remotes to shame.
The missing piece of the puzzle was my screen. I had an Elitescreen 1.1 gain tensioned dropdown, and aside from a few sparkles, it was quite good with the 665. It wasn't until I tried several Acoustically Transparent samples with the 665 that I realized the importance of a perfectly SMOOTH and FLAT surface for 4K resolution. All the AT materials I tried were fine at 1080p, but at 4K the pixels were so small that any tiny crenalations of the woven materials sent the light back at a different angle and massively softened the image. The only material that didn't was an old-school micro-perf, and that was because it was essentially flat. But the holes lost a lot of light and made white scenes seem a little dim and snow a little brown. After seeing the AT screen options ruin so much of the sharpness I bought a true 4K projector for, I gave up on the idea of AT. I can live with a speaker underneath the screen much more easily than a picture I know used to look much better.
So I got a 123" diagonal 16:9 Stewart Cima with the 1.3 gain "Neve" material from Mike Garrett at AVS. The 665 is moderately bright, but that's a big screen and I like a little ambient light so I can see what I'm eating, so I wanted a little gain. I was concerned about the gain causing sparkles or hotspotting, but this material is amazing. It's extremely smooth, and the coating that gives it gain is such a microscopic fineness that there's just zero sparkles or hotspotting. I still run my lamp in high for HDR, but I can easily run it on low for everything else. It's so flat and perfect, that the 665 appears to be putting out higher resolution! It's actually just the sharpness of these tiny pixels reflecting back more correctly from the flatter surface.
Anyway after three 4K players and testing 5 screen materials, I would confidently recommend this combination to any 665 owner.
Sony VPL-VW665ES 4K HDR Projector | Denon AVR-X7200WA Reciever | Philips BDP7501 4K Blu-Ray Player | GoldenEar Triton One, 2+, Aeon 3, HTR-7000 ATMOS speakers