A DAC to beat NAD C541i?


I've had NAD for about 6 years. It used to be a good one 6 years ago in my system, but now I think it is a bottle neck in my current system -- Tyler Taylo 7U, Linn AV5105 amp, Rogue Magnum 99 preamp.
My friend brought his Rega Apollo CD player and compared it with my NAD on my system, but I did not hear much difference, except Apollo sound a little bit more warm. But I liked NAD's more bright sound.
If Apollo is a real good one at $1000, I guess I need to spend over $2000 for a new CDP to for better sound.
Instead, if I want to go for DAC with NAD, which DAC (at $500~1000) would be best to beat both Apollo and NAD?
Which CD player (used at $500~1000) would be far better than Apollo or NAD?
Thx
ihcho
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
I think most reviews on Paradisea+ are correct: provide warmer sound but lose some detail, except that I did not experience wider sound stage with Paradisea+. DR700 even provides better dynamics.

DR700+Paradisea is more pleasant to listen than C541i+Paradisea, but still DR700 alone is better for me. Paradisea may be different on ss preamp.

OK, enough for now. I will get back when I have a new digital cable (1.5m).