Would love to help but im a bit clueless, what I can add is that I have an independent amp with 2 main speakers, a central one and a sub woofer. The only useful thing I can add is that through my xbox, pc and tv, everything sounds amazing and it isnt a complete (all in one) system, dunno if it'd be cheaper to build one yourself or not? I never really looked, all my stuff was handed down to me from mates.
The speakers/subwoofer are all Acoustic Energy and the amp that powers it all is labeled Musical Fidelity, thats all I can say about them
The biggest difference I noticed with them when moving to this flat was the sound quality when I bought really expensive cables, I'm sure theres folks on the music forums that spunk over the thought of cables, I've no idea why one sounds better than another but the pricey ones are noticeably better.