UPDATE:
In my 13.5 feet x 10.5 bedroom, I have setup Dali Oberon 5 pair as front L and R. For now, Dali Zensor 1 is connected as center speaker. Now, I am looking for a Dali Oberon vokal and subwoofer (not in a hurry).
Observations:
1. Earlier, when I was using Zensor 1 (sensitivity 86.5 dB) as front L and R (no other speaker). I somehow felt my AVR (Yamaha RX-V4A) was not able to drive them well. It felt underpowered. With Dali Oberon 5s (sensitivity 88 dB) as front L and R the sound is louder (needless to say bass is far better). The AVR does not feel underpowered (comparison done in stereo mode)
From what I have read/watched in last 1.5 years, if not for the sensitivity difference of 1.5 dB, the AVR should face more difficulty in driving a floor standing speaker than a bookshelf speaker.
2. The 3.0 setup is not fatiguing (till now), even at loud volumes. I watched 'Made in Heaven' Season 2 on Amazon prime. 3 episodes back to back did not sound fatiguing.
3. Bass of course with FS speakers has improved a lot. For particular scenes, the bedroom from outside sounds like a theater.
This gets me thinking - A 5.25 inch low frequency driver, driven by an AVR which supplies at max 80 Watt to the speaker is able to produce very good bass (for my bass appetite; I love bass). Do I need a 12 inch subwoofer with ~300Watt RMS or a lesser powerful subwoofer would do?
Adding proper center channel speaker and subwoofer in coming weeks/months should improve overall experience.