How many watts??

More information is needed, specifically what are the speaker's rated sensitivity.

It is a hypothetical post or a troll post.
So I am not sure that more information is need? It is either answered generally and hypothetically or it is not.

Many amp designers say amps tend to work at their most linearity at around 20% of their full rated output. As has previously been posted, volume increases require logarithmic power output. Having an additional 80% of total power output for headroom is prudent. Running out of power; can lead to clipping; clipping can lead to speaker damage.
Speaker sensitivity, room considerations and desired volume levels will ultimately determine how much power one needs.
There used to be an oft repeated audiophile general rule of thumb; "double the manufacturers minimum power recommendation".

Hello,
I usually listen at modest volumes. Probably 60-70db and even a lot lower at sometimes. I was never impressed by playing loud. I am more impressed by how low you can play the volume and still hear the full dynamic range. One way to cheat this is add a subwoofer so you can still hear that deeper bass. I will tell you the preamp or preamp portion of an integrated amp is most important. More important than 80 watts or even 1000 watts. The amplifier is amplifying what the preamp sends it. Garbage in, garbage out. If you hear a his, hum, or distortion why would you want to amplify that. I have seen a 10w per channel integrated tube amp rock out. You should try it. But it’s the preamp, not the amp doing that. Your system is amplifying garbage from the preamp. If you can hook up a good preamp to your system you will understand what I am saying. If you are in the Chicagoland area borrow a Rogue preamp from this store to hear how good your system can sound. https://holmaudio.com
they let you demo in your home before you buy. No more buyers remorse. 

Watts are only one small part of the overall equation of how much power an amp has. Too many people get hung up on watts and db’s. Yes numbers can be a good starting point but never stop there. Example 1 watt from a class A amp is nowhere close to 1 watt from a class D amp. Its like comparing the horse power of a lawn mower to a motor cycle. The number can be the same on paper but the end product is nothin alike.

Its like comparing the horse power of a lawn mower to a motor cycle. The number can be the same on paper but the end product is nothin alike.

Yeah… I agree that my John Dear mower is nothing like a Kawasaki motorcycle. They are both green, and have engines, but after that…

James Watt, who coincidentally standardised the unit of Horse Power, later the “metric horse” became labeled as being Watts and kilowatts…
So to claim that a watt is not a watt, only means something in the context of asking a two different 1W amplifiers to give 2 watts… and how they clip.

I quest that the OP likes it quiet. The average person needs the 50W amp that the manufacturer recommends. And there is another Gaussian tail of people on the right, that will blow the speaker apart. We can call these the 65dB, 85dB and 105 dB groups… or the A, B and D groups.