YEah, gotta know what your source is/will be.
Unless you have an existing library of music in some other format to use, like vinyl or tape for example, then digital is the place to be these days for starters.
You can use an existing computer as your main source for digital either by streaming from the internet (many very good quality music stations/sources there for free) or buying and downloading files, or by ripping CDs.
Then you do a digital connection from computer as a source to play music on the music system to-be. Many ways to do this connection. USB is a popular way to do this. Wireless Wifi network connections another. FOr Wifi, you need Wifi on teh other end as part of the hifi system. SAme for USB.
Then you need an amp and speakers as discussed, just like in the olden days....
Do not think in terms of traditional pre-amp/amp terms. You need a device to do those functions, but these come in many forms these days. At minimum, you need to be able to connect your digital source (via wired USB or wireless Wifi most likely) have a volume control, and an amplifier suited to drive the speakers well. This can all be in one or many boxes. One box keeps things simple for now. One box is essentially a modern integrated amplifier, like those from NAD for example, but geared mainly towards modern digital source gear. AN extra traditional line level input is all that is needed to start to add a phono or other analog source later if needed (or not).
One other important thing to mention with a computer as a source is to make sure all your valuable music files get backed up and can be restored reliably, just like with any important/valuable computer files.
