The Samsung HTAS1 seems to be a good fit for what your after.
If youre interested I would urge you to check out this thread:
Any thoughts on SAMSUNG - HTAS1
BTW: Most current dvd all in one systems include ways to connect other components. The more modern components, e.g your ps3 connect audio mainly through optical (spdif/TosLink) as this can carry all the data for 5.1 surround sound through one cable instead of 5!
Separates / AV amps & receivers have multiple video and audio connections so all audio visual equipment can be routed to your tv through a single connection, e.g hdmi. Useful if you have 1 hdmi port on your tv but more than 1 hdmi capable device.
Hope this helps