Preamp or DAC

I would look at the Ayon S 5 network player. This functions as a pre amp, incorporates a Dac and uses tubes.

@audphile1 is correct about the impedance matching.

However the input impedance, single ended, into the Coda 16 is 50K OHMS. Balanced input, the impedance is 10K OHMS.

If a single ended preamp is chosen, the 50K input should be just dandy for the majority of preamps available.

Regarding the Coda 07X, I recently replaced mine with an Audible Illusions L3A. Purchased it on a whim never planning on it overtaking the Coda. Alas, it did. The Coda has way more remote control features plus gain matching the inputs is super great. In the end, the A.I. is sonically superior to my ears. Though losing the Codas input switching via the remote control was a bummer.....

I have a similar type of system. Coda #8 amp, Holo Audio May KTE DAC, Holo Audio Serene KTE preamp and Aurender N200. I also have dual REL subs. I ordered a new BAT VK-80 tube preamp a few days ago. I’m also trying to integrate some tubes into my system. Many people I know weren't really happy with the Coda 07X preamp. You won't have any problems with impedance matching with the Coda and most preamps. The 10-1 ratio will be easily met with most preamps and your amp.

@backdoor

With your $12k - 15k budget, get a used Aries Cerat Incito S preampfifier or Helene DAC. Either unit will greatly transform your system and it’s worth every penny. It’s just extremely hard to find a used / demo unit in the market.