+n to what our other friends said.
Friends don't let friends buy preamps when they could buy a really big sub to annoy the neighbours with?
Most rooms will do fine with a receiver rated at 90-100 wpc (two channels driven).
Most of the time, you are going to be using less than 20 watts to enjoy your system at a reasonable listening volume.
The exception is when your system is in a very large room AND you are listening from further away. In most cases, I expect that the listener is going to be in the range of 10-12 feet from their speakers.
Get a better sub so you can really enjoy the deep rumble in all those awesome action movies.