1-buy speakers that have a matching center channel if you need it.
2-either start with a stereo amp that the manufacturer makes a matching 3 channel amp or a find a multi channel amp that is bridgeable so you don't waste channels for now.
3-To get an audiophile quality pre-amp that will expand to 5/6/7 channels may break your bank and even be obsolete by the time you need it. Consider something like an Anthem AVM-2 which sounds awesome in stereo or multi-channel with great built in d/a and a nice tuner (this is just an example like B&K, Sunfire, etc...). You can get one used for around $1200. This way, if you get the upgrade bug you will have it. The unit has already been hit with depriciation and you won't take much of a beating selling it if you want.
Finally, I tried the same route as you and ended up with both theater in one room and 2 channel in another.
Good luck!
2-either start with a stereo amp that the manufacturer makes a matching 3 channel amp or a find a multi channel amp that is bridgeable so you don't waste channels for now.
3-To get an audiophile quality pre-amp that will expand to 5/6/7 channels may break your bank and even be obsolete by the time you need it. Consider something like an Anthem AVM-2 which sounds awesome in stereo or multi-channel with great built in d/a and a nice tuner (this is just an example like B&K, Sunfire, etc...). You can get one used for around $1200. This way, if you get the upgrade bug you will have it. The unit has already been hit with depriciation and you won't take much of a beating selling it if you want.
Finally, I tried the same route as you and ended up with both theater in one room and 2 channel in another.
Good luck!