If we're having THAT kinda budget, then (the upcoming) Wadax Atlantis Reference Transport should be able to beat just about any kinda 4K UHD Blu-ray players out there.
FYI - here's what the OP of this thread mentioned last year
https://www.whatsbestforum.com/threads/new-wadax-atlantis-reference-dac.27860/page-9#post-644026
Their flagship Atlantis Reference DAC was fed by Extreme
https://www.facebook.com/TaikoAudio...ulder-vimberg-ultimate-audio-/526128508266069
Ultimate Sessions Porto by Ultimate Audio Elite with Vimberg Tonda D speakers, Boulder 2160 and 2110, Wadax Reference DAC, Taiko Audio Extreme server and Siltech Triple Crown Cables.
https://www.monoandstereo.com/2020/07/blog-post_6.html
Not their best transport by any means but it does play all kinda Blu-ray discs with an optional video module, and most likely it's one of the best SACD rippers on Earth
http://www.wadax.eu/?q=atlantis/transport
I don't mean to be disrespectful at all, though I'm just wondering if there were anyone who compared Extreme to their Atlantis Reference Server?
Other than that, I could only think of something like this but IMHO it's gonna be quite difficult to find something with high "Spousal Acceptance Factor" that's able to handle such *.MKV container
- Rip 4K UHD Blu-ray discs to the *.MKV container
- Demux the audio track and downmix to 2 channels
- Upsample with PGGB Offline (16FS / 32FS)
- Mux the upsampled audio track back to the original *.MKV container