I would really suggest a pre-amp with multi-zone capabilities. If theater isn't involved, the adcom is a really inexpensive option. Be careful with home theater receivers with multi-zone outputs, many don't do everything you want. Niles makes a much more expensive version of the same thing.
The other option since you have systems in two other locations: Use the multi-room outputs with a pair of "Y" adaptors. You can run this line level to each pre-amp using CAT-5 wire. You may want to consider hooking up a remote eye at each end also so you can control this main pre-amp with a remote in each room?
The other option since you have systems in two other locations: Use the multi-room outputs with a pair of "Y" adaptors. You can run this line level to each pre-amp using CAT-5 wire. You may want to consider hooking up a remote eye at each end also so you can control this main pre-amp with a remote in each room?