Is the TX-NR6100 good for a 5.1.2 Dolby Atmos setup?

Yes. It powers seven channels, so it can run a 5.1.2 layout with two height speakers, or 7.2 without heights. Dolby Atmos Height Virtualization can simulate heights from a 5.1 or 7.1 setup.

Does it support 4K/120Hz and VRR for PS5 and Xbox Series X?

Yes. Its HDMI 2.1 inputs pass 8K and 4K at 120Hz with VRR, and it supports HDR10, HDR10+, Dolby Vision and HLG.

Can I use it with two pairs of speakers in different rooms?

Yes. It has a powered zone 2 output, so you can run a second pair of speakers in another room while the main zone plays a different source.

Does it have a phono input for a turntable?

Yes. There is a built-in moving-magnet phono stage, so a standard turntable with an MM cartridge connects directly without a separate preamp.

How many subwoofers can I connect?

Two. The receiver has two subwoofer outputs, which helps even out bass in larger rooms.

Is it worth choosing over the TX-NR5100?

The NR6100 adds THX certification, more power, a second HDMI output, a phono stage and zone 2, so it suits larger rooms and multi-room use better than the cheaper NR5100.