skuller

I am installing a carputer on my second car
The thing is I want to sell the car in the next 9 months or so.

I would use onboard soundcard (with line out), and factory speaker (4 speakers)
I talked with the crutchfield guy and he said I would burn my speaker immediately if I use aftermarket amp since aftermarket amp give out a lot of power.
I am not going to buy any aftermarket speaker for this car.

everything that I installed on this car would be removed at the time of sale.
So the least the better.

Any idea?
also, the computer would replace the factory hu, so aux in is not an option

thanks