A DAC to beat NAD C541i?

I'm guessing you're perhaps missing some dynamics and extension due to relatively high output impedance of the tubed Paradisea+ DAC. Do you have better dynamics using the solid state CD players? Solid state players usually have low output impedance.

I don't think changing the Toslink cable is going to make a bit of difference. A tube change will make a subtle difference, but it won't be dramatic.

PS- you might get better and more noticeable results from a solid state DAC due to the lower output impedance.

The cable is 1m. Any reason why it has to be 1.5m? I've been looking for a new digital cable and will try one with 1.5m.
C541i alone sounds a little bigger than C541i+Paradisea. Yes, I felt a tad bit more dynamics with C541i. But the bigger difference is the warmth -- with paradisea it sound a bit warmer. Same feeling I had when I compared C541i with Rega Apollo which sound a bit warmer than C541i.
C541i alone sound more bright, and at full orchestration it sound a tad bit more muddy than with paradisea.

Anyway I like DR700 better than C541i or C541i+Paradisea. I wanted to use DR700 exclusively as a CD recorder, but if the paradisea does not open up with cable change or tube change, I may stick to DR700 and forget about DAC for a while. I guess my tube preamp (Rogue Magnum 99) is doing an excellent job in pulling all strengths from SS CD player, so I may not feel much difference unless I go for much higher upgrade.

Many thanks for wonderful tips.

You're apparently dismissing the point of impedance match. You don't have to spend more than you did on the Paradisea+ to achieve a better impedance match, and thereby get better possible results (bigger sound, better bass and treble extension).

Any SS DAC would better impedance match with bigger sound, better bass and treble extension? Then probably I would give another shot. Any suggestion?
I would expect the similar amount of improvement from Grado gold to AT150mlx. LOL