Speaker power question.

[Nostromo2]

I seen recently table that shows how big room e.g. (7) square meters can cover e.g. 7Watt (RMS) speaker. Can someone remind me where i find it?

Also i thinking to buy BoomBox that supports MP3 format, i only found 1 good choice, but it has only 2.5Watt RMS Speakers, isnt it to low, wont i make fatal mistake buying it?

Thats the device Thomson TM9670

Heres the spec:

 

[Kenyada]

2.5 RMS speakers are smaller than the speakers one would place in the front door panel of a car... a very tiny car. Sure you will get sound, but it won't be very good.