I currently have a LG LHT764 system hooked up to my 42" plasma for my sound. I would like to upgrade my audio system but I am not sure where to start. I can't buy it all at once so I am basically asking what to do first. Do I keep the LG amp and start adding speakers in pairs to it than end with buying a new amp. Or do I start with a new amp than slowly add the speakers to it?