Yes, Amazon UltraHD preferred partners list is here:
https://www.amazon.com/b/ref=s9_acss_bw_cg_AMHDFAQ_md2_w?node=14063680011&pf_rd_m=ATVPDKIKX0DER&pf_rd_s=merchandised-search-5&pf_rd_r=RF10X3D09K7G2F3T8YKB&pf_rd_t=101&pf_rd_p=8a024364-032a-457c-ac7c-a4f8b1d51579&pf_rd_i=14070322011#hd-edu-brands
And looks to be mostly made-up of conglomerates;
Sound United (Denon, Marantz, Polk, DefTech, Boston, Classe'),
Samsung/Harman (Arcam and many many others)
Lenbrook (NAD, Bluesound, PSB)
Bagby (Paradigm, Anthem, Martin Logan)
McIntosh group (Mc, Sonus Faber, etc.)
Voxx (Klipsch), Rotel (B&W), and the typical big home audio icons, Sony, Pioneer, Onkyo/Integra, Bose.
And looks to be mostly made-up of conglomerates;
Sound United (Denon, Marantz, Polk, DefTech, Boston, Classe'),
Samsung/Harman (Arcam and many many others)
Lenbrook (NAD, Bluesound, PSB)
Bagby (Paradigm, Anthem, Martin Logan)
McIntosh group (Mc, Sonus Faber, etc.)
Voxx (Klipsch), Rotel (B&W), and the typical big home audio icons, Sony, Pioneer, Onkyo/Integra, Bose.