Redtruck65MA,
Here is a little history:
In the early days of radio, they designed speakers that were a marvel at the time but they were large , heavy and inefficient. Then, by the time the fifties rolled around, they had small light speakers that didn't take a lot of power to perform their magic. The radios in the AD trucks for example had undistorted power output rating of 2.4 watts and a maximum power output of 5.4 watts. If you have ever listened to one of these radios you know that they can perform at an adequate volume.
As time progressed, there was great interest in faithful reproduction, introducing the concept of "high fidelity". The design focus then turned to the accuracy of the system and little attention was given to efficiency. There were speakers that were developed that wouldn't work properly unless you had an amplifier good for 50 watts.
Nowdays, we are somewhere in between the two extremes. There are auto sound systems that can produce huge power outputs and I would suspect that some of these are used to drive those sub woofers that we hear from time to time.
To answer your question, the power output should be such that it will driver the speakers properly. Personally I can't imagine using over 100 watts but then I don't enjoy loud situations.
The watt power rating has nothing to do with how well the tuner will receive weak stations. This is usually given in the selectivity and sensitivity figures.
