Does the JBL Bar 300 MK2 come with a subwoofer?

No. It is a 5.0 all-in-one bar, so bass comes from the bar itself. Expect less low-end punch than a system with a separate subwoofer.

Does it support Dolby Atmos?

Yes. It decodes Dolby Atmos and uses processing to create height effects from the single bar. The effect is subtle compared with a bar that has up-firing drivers or rear speakers.

Will it pass through 4K Dolby Vision from my console or streamer?

Yes. The HDMI port supports eARC and 4K Dolby Vision passthrough, so a device connected through the bar keeps its picture quality.

What is room correction on this bar?

Room correction adjusts the bar's sound to the acoustics of your room. It helps in small or oddly shaped spaces where walls reinforce some frequencies.

Is it good for a small room?

Yes. The compact size and one-box design suit small and medium rooms. It fills those spaces well, but it will not deliver the bass or surround scale of a bar with a subwoofer and rear speakers.