[sergejskr]

Its was some UHD mkv rip..

Its more likely you have override picture settings in OPPO
as it doesn't make sense you are comparing via feeding ZIDOO into OPPO HDMI IN, the results are slightly better because of more correct brightness and contrast adjustments.
To make them 100% comparable, you should calibrate your display for OPPO source and calibrate your source for ZIDOO source, then do a comparison by playing content from OPPO and from ZIDOO separately, not via feeding ZIDOO into OPPO HDMI IN.