Audio Systems: We need a loud system, external amplifier, home theater system

Question
So lately my family has been disappointed with our home theater system (it's just old).  We want it to be a lot louder.  I've been doing research all day looking at home theater bundles and such, but just can't seem to pick one.  I've looked at sony, energy, and a few other well known systems.  My father (yes I am the son of the family who has been nominated to pick the system), seems to think our speakers are fine, and that we just need a new receiver.  So if our system will not get loud enough, is it due to the speakers or the receiver or something else?  What system or receiver should we get that is under 800 dollars? Thanks for your help.

Answer
You did not give me any information about the existing system.  It may just need an external amplifier to feed the speakers.  But, if the speakers cannot handle additional power you would need to replace them as well.

I will await your follow-up question in which you should include the make and model number of the set you are currently using.  Also, give me some idea of the kind of music you listen to and the size of the room it will be installed to.

Loudness is only one aspect of the quality of a system.  For example, if you not only want louder sound output but lots of bass output you will need to add a subwoofer system as well.  So, tell me more and we can go the next round.  If you have been looking at some systems let me know what you have been studying.

PS: I do not make equipment recommendation because there are too many subjective factors involved but I can guide you on how to make the selection based on your own criteria.