Maybe i have this wrong but lets say i had a 500w head at 4 ohms. And that went into a cab rated at 500w at 8 ohms. i would get less than 500w of power because of the resistance? so if i wanted to make the most of my cab could i buy a 600w head at 4 ohms to make up for the lost watts due to resistance?? correct me if i got that totally wrong lol and if i was right about the ohms, would that be a good idea?. cheers!