From my perspective...it is all about the volume peaks that you would require at your listening position...so as an example...a 6 ohm average speaker with an 89db sensitivity ...listening 10' back with 91 db peaks...will require in the 25 watt area...assuming the peaks jump above 91 db...you could easily hit 50 watts....and where the speaker dips below 6ohms...even more is needed.
So, the answer is dependent on...what is your speaker sensitivity...how far back do you listen....how loud do you listen. Purely from a safety standpoint, more watts are better...meaning you are much less likely to have clipping distortion damage the speakers.
If you want small...then the PS Audio sprout, which has a good reputation for sound...might be a better solution as it is 50 watts at 8ohms and 100 watts a 4 ohms...and I'm sure there are many more good sounding options that are more powerful, yet small.