This Might Not Exist, Any reasonably priced, smaller speakers with 100db Sensitivity?

95db sensitivity, not big, 700/pair

With 2 watts, you'll probably be sitting at 90db-ish with decent enough bass in that 12 by 10 room.

https://tektondesign.com/product/full-range-speakers/monitors-loudspeakers/mini-lore-monitor/#color

If you wanted 100 db sensitivity for a similar cabinet size, it will be a bass-less speaker (such is the physics).

On the same note, 3.5 Watts sounds like a lousy amp.

Try something like this instead, 10 watts @ 8 ohms, 15 watts @ 4 ohms, 30 watts in mono mode.

https://www.schiit.com/products/gjallarhorn

 Good quality speakers  to meet the  100 db , small and budget ??   If you get above mention speakers , you need extra subwoofer

The 3.5 watts I mentioned was hardly from a lousy amp. I was referring to the outstanding Triode Audio Labs creations. 

Closest to what you’re describing. 3.5w goes much further than you might think…

https://www.zuaudio.com/loudspeakers/p/mb1

Quality sensitive speaker at a low price = Tekton.  

Polycell 15 is 103 dB.

Perfect SET is 98 dB (there are two versions)  It should be fine and I have a friend whose pair sounds great.

I have successfully driven Encores (96dB) with a 2 wpc Decware EL84UFO.

Some people don't like the looks.  Also some jump to conclusions that these speakers ahe a huge array of tweeters.  They have one tweeter.  An array of the same small drivers is also used as a midrange.

Jerry