Noob help with home theatre setup (1 Viewer)

[Andysk]

Hi All
I am looking for some help in doing up a new (or used) home theatre set up and getting better components. I currently have an onkyo tx-sr605 receiver that does all the work for my 7.1 set up . I am wanting to look at starting to put together something a little better but using individual components.
Can someone tell me what components I need to look for to put something together. I want to also run a phono record player as well and my Onkyo doesn't have any phono pre outs.
Current Setup:
Definitive BP 7004
Definitive CLR 2300 Center
BMPX Bipolar Surround x 2 pairs
Onkyo TX-SR605
Pioneer BDP-120 Blue ray player
PS3

 

[Mr645]

Other then photo inputs which can be solved with this http://www.amazon.com/Parasound-Zphono-Phono-Pre-Amplifier/dp/B001KALK4Y
What are you looking to improve?
Marantz makes a great processor and there are a lot of choices for amps out there.
Speakers have the greatest effect on sound quality. I am not very familiar with Def Tech products, but perhaps moving up the line would help.