Hi Curious! Select features provided by the HW-Q950A are only compatible with Samsung 2021 TVs. With the 75" Q90R TV, you will not be able to take advantage of features such as Spacefit Sound, Q Symphony, or the full eARC connection. You will still be able to take advantage of the powerful 11.1.4ch surround sound giving you our most immersive audio experience yet. For additional assistance with compatibility to your 75" Q90R you can contact us at 1-800-SAMSUNG (ask for Soundbars), 8AM -12AM EST (Mon-Fri), 9AM – 6PM EST (Sat), text HELP to 62913, LiveChat on Samsung.com, or Email: https://www.samsung.com/us/support/#contact_us_for_support
^Tim