it is ok... but you loose the RCA signal strength when you do that...

Pros:
1. you could still get music for all the amps you connect it to.

Cons:
1. Low signal strength means higher gain from amp which means possible of distortions.
2. no fader control.
3. if your amp doesnt have a built in x-over you will have trouble getting the sound right.

i guess that depends on the brand's normal habit of printing these numbers...

some brands like sony puts up ridiculous claims on the wattage, which normally is their max rating,

some brands like TruTech doesnt print anything but their amps model number has a clear indication of the rms wattage value...

some brands like rockfords, well, sometimes i just dun undertsnad what the numbers means....

so cant tell you exactly...

there are device that you could use to measure...

1. multimeter... but you will have to convert the values to watts rms... which involves some equations...
2. wattmeter... which displays the power output directly but these machine are hard to get by and expensive...