What is most important part of a system?

great question , but its all important garbage in garbage out so a good front end is important, the right speakers are also just as important they all sound different in my room anyway , room acoustics very important or your never get the best out of any component, a better quality sounding amplifier can make a huge difference to sound quality ie going from a good ss to a great valve or vacuum tube amp is an incredible experience ,also trying a passive pre amp can be incredible also but im going with the front end as the man behind linn said garbage in garbage out , another wise man once said you cant polish s**t

if its a case of where to spend the most money, in this audiophile life we have never usually really got enough money so my go at answering this question is now going to be speakers, having great speakers at least makes sure that you have left the best till last and whatever signal has been achieved by your system it will not be getting held back at the last part of the chain, garbage in garbage out will still be playing a big part here but at least the speakers will be as good as you can get , no good spending most of your money on a piece of equipment further up the chain if you have got a pair of s**t speakers  , so on a budget the new answer is definitely spend the most money on the speakers , room acoustics are a big issue but very simple free ideas like hanging curtains around the walls and adding some soft furnishings like rugs and cushions usually can tame a lively room , using simple 40gbp RDC cones under your speakers is a good prity cheap solution , so where to spend the most money will be speakers definitely.