as a person known for building a system without gear limits or room limits, it's easy for me to say the most important thing for me has been the sonic reference in my mind i am trying to attain. as my sense of where i'm going has progressed, my system performance has followed. and recent room tuning success was tied completely to my minds grasp of the goal. previous frustrations were tied to a less than clear target.
if we are ranking pieces of a system in order of significance, then the whole speaker-room interface is dominant. are the speakers scaled to the room so the music works in the room? some speakers are more flexible than others. some driver topographies are less room dependent than others. but at the end of the day you cannot overcome this obstacle. and if this is right, you can go modest levels of everything else and you can have excellent music reproduction.
next is the amplifier-speaker relationship. can the amplifier properly control the speaker? and is the tonal and dynamic synergy good? again; getting this right makes everything else pretty easy.
preamps are important, especially at the top of the food chain. and an uber system needs a great preamp. but at more modest levels of gear sometimes eliminating the preamp is actually preferred as it can get in the way. there is not one truth in this issue.
these days sources can be very modest and yet make great music. so again the significance of sources depends on the overall level of the system. at the top of the food chain they are limiting, but at modest levels lots of choices work great.
(1)have a reference in your head at to where you are going, or trust someone who does. (2)get the speaker right for the room, and (3) an amp that works well with the speaker. get those right and you are in pretty good shape.
