Well, since you asked for more explanation:

The main system is in the living room (Zone 1); we use it for watching TV, DVDs, listening to the radio, music CDs, sometimes video games, PC music.

We also have a pair of speakers in the kitchen (Zone 2), with two pairs of (14AWG) speaker wire run through the walls from living room to kitchen.

Sometimes we're working or sitting in the kitchen and we'll listen to the radio or music there.

Sometimes we're watching TV or a DVD but want to go check on something in the kitchen, can't or don't want to pause, so we want to turn on the (same) sound in the kitchen as is on in the lliving room.

So, combinations used now:

Zone 1: sound off; Zone 2: radio or DVD.
Zone 1: TV, DVD, radio; Zone 2: either off or set to the same

Desirable combinations (also supported by HK635):

Zone 1: game, TV, DVD; Zone 2: radio

The HK635 can support this, if I can figure out a way of controlling it that makes sense.