Samsung Q600b a good option to have a little bit of Atmos experience? Couldn't find much reviews online about it yet, mostly on the Q600a model.

Yes it's just for a small room. So far I found this model and LG SN7Y which have a dedicated up firing speakers to mimic the real downfiring Atmos speakers. I know we won't get real Atmos experience below 2k budget, at least if I can hear something flying above like in the movie, that's already good enough.

440w is SN8Y

Q600a does not have WiFi capability. I noticed that RTings rated the Q600a a bit higher than the more expensive Sony G700. The Sony has good performance for movies but a bit lacking in music and dialogue clarity. Having a Sony TV making me inclined for another Sony devices but the Samsung is more future proof. It also cheaper to buy the surround speaker kit if I want to transform it to 5.1.

Bluetooth

for full atmos effect then yes. as you can see from the picture, the rear speakers has front and up firing drivers. the sound from upfiring one needs to be bounced off from the ceiling. if the rear speakers sit very close to you, you won't hear the back and above sounds, instead it will end up in the center.

I bought the q800b because my sofa already close to the wall so there's no point on having rear speakers. Previously had a 5.1 home theater and I had to put the rear speakers at the top. Watching Stranger Things on Atmos is amazing, with volume 20 it already filled the room. I had to tone down the subwoofer a bit because it rumbles like crazy.

Same price but sonos doesn't have subwoofer. How to enjoy atmos content without sub?

I know it support atmos but without sub you cannot get the thumping sounds and loud rumbles.

I believe Q930B is for bigger room where you have some distance between you and the back speakers. I bought the Q800B because my sofa already close to the wall, the audio would have messed up if I put the rear speakers just behind it.

Also point worth noting, up firing speakers for atmos won't have good effect for ceiling around 9 feet high and above. Although dolby mentioned 12 feet max but some people have tested and couldn't hear the effects even in 10 feet ceiling room.

Each rear speaker has own power plug and they connect wirelessly to the soundbar. I think the cable is around 1.5m length.

How far is the wall behind the sofa?

I follow RTINGS suggested settings like below

Voice & bass enhancement OFF
SpaceFit ON AVA OFF
I increase a bit for Side speaker level

Higher watts louder sounds even at lower volume. Lower watts you need to crank up the volume, at high volume usually will lose sound clarity because of distortion.

My first home theater setup was a cheap sony 5.1 bluray player with 300w total output. Volume had to be 80 and above if I really want to enjoy the sound. After few years it started giving error push power protect if I use it for long hour sessions, dropping the volume to 60 something would solve the issue. It was like cpu throttling in pc whenever a temperature threshold is reached.

I believe nowadays speakers are made from better materials, 175w maybe sounds a bit low but it probably good enough to fill a small living room. But then asking 1.9k for it is ridiculous.

If got issue how to claim warranty?

300 charge for unboxing and putting it on the table top?

All depends on audio source. If your TV box supports atmos then no issue lah.

I believe for the 1st method, the soundbar needs to have hdmi passthrough feature. For the 2nd method, the TV needs to have audio passthrough feature.