DAC upgrade suggestion


I am currently using a Audio-gd nfb 3.1.  The information below.  I bought a Topping DX7 pro based on the good data in audio science review.com.  When I first use it, I can hear the difference immediately.  It is more dynamic, bass is more punchy, sound clearer.  It sounds great.  But after listening for a longer time, I feel a bit fatigued.  I can compensate it a bit by switching the tubes in my amp.  Then, I need to return the DX7 because the Bluetooth doesn’t work.  I plug back in the Audio-gd, and i can confirm it is not fatiguing.  It is less dynamic, but also smooth.  Now, I am confused on what I should upgrade.  Several Audio-gd DACs are reviewed by AudioScienceReview.com and the data is very bad, LoL.  I know the bad data doesn’t mean it sound bad, but should I avoid DACs with good data?  How should I pick my next DAC?  It seems R2R DACs maybe a good choice for me since many people says the sound is more analog-like.

http://www.audio-gd.com/Pro/dac/NFB-2/NFB2EN.htm
gte357s
All of these posters rave about how superior the R2R DAC's are....yet I suspect none of them have heard Lampizator's  DS53 digital engine, a derivative of the digital engine used in their Pacific DAC. They’ve standardized this Delta-Sigma design throughout their line, and to my ears it's sonically superior to R2R designs.
I think your system determines what DAC sounds good with it.

My Thiel CS5's, yeah they are old speakers, can sound a bit piercing in the treble if one is not careful with equipment matching. 

I tried several DACs in the $1K to $2K range and they seemed a bit "tizzy" to me in my system. I settled for a Hegel HD25, which came close, but it still was not quite right.

Took a chance on a old Theta ProBasic III R2R DAC for like $500 about 18 months ago.Sounds great to me with a PS Audio PWT. Not sure if it sounds more analog like, but to me in my system, it is a bit smoother with no loss of detail. 

Thanks for listening.
Audio gd just look at the forums digital is supposed to run cool not gd ,they run hot and horrible distortion specs look at audio science forums and plenty other board failures thats why I bought a Denafrips runs cool and exceptional low distortion .
@three_easy_paymentsJust listen top what 

"All of these posters rave about how superior the R2R DAC's are....yet I suspect none of them have heard Lampizator's  DS53 digital engine, a derivative of the digital engine used in their Pacific DAC. They’ve standardized this Delta-Sigma design throughout their line, and to my ears it's sonically superior to R2R designs.

Yes-- to their ears, R2R DACs are "superior"-- to your ears, the Lampizator Delta-Sigma is "superior". This "proves" nothing, except that each person hears differently, has different concepts of what sounds "best" to them, and is most likely listening on different gear (and obviously) in different rooms.

There's no guarantee that fans of R2R DACS would prefer the Lampizator just because you do!