I think he is worried about the amp putting too much power to the sub,
I always try to power my speakers with a amp that is double the rated power of the amp.
this will assure you have "headroom", better efficiency, cooler running longer lasting amp.
all you have to do is be mindful of the gains and settings and you won't have any problem.
An amp does not put out its full rated power all the time, in fact a 800w amp can be adjusted to put out only a small fraction of its rated power.
Tell your dad that lanzar,pyle,hifonics, and basically every good brand that was around in his time. They have all been bought out and shipped over seas, they are no longer respectable audio company's like they were back in the days when he was into this stuff. A LOT has changed since then. quality equipment is more difficult to find these days, unlike back then when almost everything was well built.
with all do respect, and the best intentions, he needs to brush up on his audio a bit.