What's the best approach?

Here's the situation: I'm replacing a 16-year-old 2-channel system consisting of cd/dvd player for source, speakers, tube preamp, and a SS amp. What is the best process to follow in doing so? The question isn’t about specific types or brands of equipment, but the approach one takes. Should one start with speakers, then match an amp, preamp, and source? Or start with the best source one can afford and work out from there? Is there a logical process for building a balanced, synergistic system? What do you think?