I have a denon x4000. Using zone 1 and 2 for stereo. I need to hook up 4 more sets of speakers. Do I use x4000 as is and add amplifier or get new receiver and use x4000 as just a amplifier for the 4 additional sets. My thought was get a new denon for the updates features and then use the older x4000 for the power. Thoughts?