You can get a multi-channel amplifier that has the ability to use a shared common input. Volume control for each channel pair (left/right) would still typically be controlled through local volume controls on the wall. There are certainly setups which allow you to use multi-source preamp units, and I'm sure similar combinations which can deliver what you are looking for, but as your configuration gets more complex, the price can go way up for quality. Generally, in a multi-zone setup, I ditch the A/V receiver for those duties in favor of a dedicated home audio distribution unit. For the money, I can often get Crestron for less than some others on the used (eBay) market, but Niles is one of several players in this arena.
