Samsung HW-Q990C vs Samsung HW-Q990D

The Samsung HW-Q990D is the next generation of the Samsung HW-Q990C. While both bars largely look the same, one notable change is the addition of HDMI 2.1. The Q990D can passthrough 4k signals at 120Hz, which is great if you're gaming from a next-gen console. It also supports Private Listening, a feature that sends audio only to the satellite speakers, which helps minimize disturbing others, and Sound Grouping, allowing the satellites to play left and right channel content for a more stereo sound. The Q990C may still be worthwhile if you don't need HDMI 2.1. Since it's older, you may be able to find it discounted, making its cost-to-performance ratio a bit more digestible.