Which is the most important part of a stereo system?


My system consists of a pair of B&W 630's, an old Denon 50 watt reciever (DRA-550) from the mid 80's, a Marantz CD5004 cd player, and now a Pro-ject Debut Carbon DC Turntable.  I'm pleased with the speakers and the cd player and while the Denon sounds good it has some issues and I want to upgrade.

I'm planning on returning the Pro-ject TT and getting a higher end TT.  I'm also looking into getting a new amp pre amp with a internal DAC.

Is the source the most important? The speakers? 

Please Help!
klimt
I'd go speakers first followed closely by the room itself.  Find your taste in the sound of the speakers you like--everyone is not the same where that is concerned.  All the other stuff is important, just not as important as those 2 things.  Know what particular cables do especially well helps to get it right near the end of assembling a system.  

Bob
@Terry9
 I definitely built a few sets of speakers, back in the day. Going to try single ended boutique amp kit next maybe with or from a Nelson pass design. 
I find that everything matters.

For me, the most important thing is the amp/speaker interface. Get it right and you are on your way to a system that can sing. Get this wrong and well, you may never get it right.
I own the 1210 GR...it’s a fit and forget audiophile TT.  It’s maintenance free and bulletproof.  Sound on mine with a Bronze Cartridge is incredible.  Buy it yesterday!