Preamp or DAC

Hello all. My system consists of the following:

Coda 16 Amp, Coda 07x preamp, Holo May KTE Dac, Aurender N20, Legacy Audio Signature SE speakers and a pair of REL 812 subs. I am considering changing either the preamp or Dac. I would like to go with tubes. Would you think I would get more sq change in changing the preamp or Dac? I am thinking Dac but I wanted to hear your opinions. Considering ARC, new Don Sachs or Aric Audio in pres and Lampizator or other in DACs. So, would the preamp or DAC make a bigger difference? I will say I have a $12k to $15k budget.

Thanks