@weinhen
1. The function of the non-oversampling R2R ladder technology will help solve some of the digital grain, and provide you "less high frequency brightness" as you are looking for. That’s part of it. Not all of it, burn-in, tubes and cables are next.
2. The stock GE 6570 or Triple Mica version of that same tube can sound a bit neutral, nice, maybe a tad tipped up on top at first ’til full burn-in, but nice and ties in directly to whatever interconnects you choose, so you are asking the right questions.
- I use the Tesla tube instead (mid level) smoothness. The WE396/2C51 is too smooth in my setup. Works for some with brighter sources and metal dome speaker systems. Let that stock GE5670 burn in for a while w/new ICs.
3. My theory is "you can easily change the tube" or "change the caps inside" for less cost than buying and trying different interconnects. Choose interconnects well w/o adapters if you can help that situation. Try CableCo for demo loaners if totally uncertain. I follow what others said, start with a first loaner pair, go +/- from there.