How much $$ do bells and whistles add to preamp?

Well, as you surmised. no easy answer, or is there?

My system is cd only. I have the Audio Alchemy DDP-1 + PS 5 (outboard PS) when available MSRP was $1995 + $695. The combo can be found ~ $1000-1200. After 2 years I am still very happy with it, BUT, have wondered about R2R dacs. There is ONE I read about recently, with an optional built in preamp in the $5K range. Sadly, I don't recall the model/brand. If I do, Ill update. Maybe someone will chime in. I watched it on YouTube

Holo (Audio?) Spring KTE ~ $4000

Just watched Passion for Sounds YT video comparing the Spring (sans preamp board) to the Schiit Yggy, which is ~ $1000 less, but he preferred it.