The difference is licensing
s905x4-
s905x4-B Dolby Digital, Dolby Digital Plus
s905x4-H Dolby Digital, Dolby Digital Plus, DTS,
s905x4-J Dolby Digital, Dolby Digital Plus, Dolby Vision
s905x4-K Dolby Digital, Dolby Digital Plus, DTS, Dolby Vision
The -K includes DTS license, but in CE the DD, DD+, DTS licensing doesn’t matter.