In addition to all of the fine advice given above, I would like to add that unless some basic attention is given to room treatment you will have sufficient sonic time smear present in the room to diminish the full effects of any meaningful improvement. Beleive me when I say that I learned this lesson the hard way. Even just the most basic set of bass traps and abfusers can deepen and focus your soundstage as well as strengthen ambients.
Order of importance
I recently upgraded my system to Thiel 2.2, CJ MF2200 and CJ PFR. I went back to using my old Denon 1520 CD player from a new DVD. I was told by a salesman that the order of importance in a system is 1)speakers, 2)source, 3)preamp, 4)amp. Therefore, I was told to buy a new CD or use the Denon as a transport and get a DA converter. Any thoughts on this and what DAC to consider?