I do not know how to cleary explain it, watts do make a difference, but not as much as advertised. there are many low priced systems with low watts that sound really good, however it is not what you would want for a party.
Then you can also have systems, which is why i want more info before I buy this thing from amazon. These systems can have high watts, 300 is pretty high for a console sound system. And it can sound like A$$.
Then you can also have the really bad home theater in the box generic systems, that are often found at walmart that are 70 watts and sound like crap.
Remember systems are in total watts, So if you have a 2.1 setup, which is 2 speakers and a sub and its only 100 watts. It would be more powerful than a 200 watt 6.1 surround sound system.
Example 6.1= 6 speakers and a sub. For a low powered sub may be 50 watts, so the rest 150 would be divided by 6, roughly 24 watts per speaker, compared to that 100 watt 2.1 system
This Amazon one is 300, which is a lot, most likly the sub is 50-80 watts, which leaves a lot for the two speakers. So from its price I would choose to believe that it has decent thump to it, and can get pretty loud, but doesnt sound that good.
Its like turning up something on the radio really loud.
Hopefully i made some sense.