Samsung HW-Q990C vs HW-Q990D

What both give you

This is the reason either is worth buying: the box contains the soundbar, a wireless subwoofer and two wireless rear speakers, in an 11.1.4 layout with real speakers behind the listener. No amount of processing from a single bar does what actual rears do.

Both carry Q-Symphony, which uses a Samsung television’s own speakers alongside the bar, and both include SpaceFit Sound Pro, Adaptive Sound and the Active Voice Amplifier. Q-Symphony works only with Samsung televisions; with any other brand you lose that and nothing else.

What the newer model adds

• HDMI 2.1 with 4K 120 Hz passthrough. This is the one that decides it. If a PlayStation 5, an Xbox Series X or a gaming PC runs through the soundbar, the D passes 4K at 120 Hz and the C does not.
• More power, around 730 W against 670 W, with upgraded converters and revised crossovers.
• Private Rear Sound, which plays through the rear speakers alone so you can watch without disturbing the room.
• Game Mode Pro, tuned by game genre.

Which to buy

If a current console is plugged into the soundbar, buy the D. The HDMI 2.1 passthrough is not something you can add later.

If nothing in your setup outputs 4K at 120 Hz, buy the C and take the discount. Once a newer model has replaced it on the shelves the price gap is usually far larger than the difference in what you hear, and the core of the system, the eleven channels and the real rear speakers, is the same.

Whichever you choose, check for mains sockets behind the seating position first. The rear speakers are wireless for audio, not for power, and that is the constraint people discover after the box is open.