What does it mean when the inverter says it is 'Modified Sine'? Do I need this or not?
And would too much Watts(600W w/1200W surge) be bad for my battery?
600W? Why do you need that much?
I don't know if it'll actually be bad for the car or computer to have such a big inverter.
But originally, I had a 300W inverter, but that induced crackling sounds in the speakers. I replaced it with a (cheaper) 140W inverter, and all is well.
I know i don't need all that power but it was cheap. If I do get this, will my speakers make crakcling noise too?
They probably mean that the output is more square than sine.
This is why cheap inverters are cheap :-P
Generally the more expensive inverters produce a better approximate to a sine wave output.