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
Thanks for all the suggestions.  Some of them haven’t heard before, Will am have a look.

My budget is < $1500.  I am ok to buy used, but those popular ones seems hard to come by.  People are hanging on to them.  =)
I love my Border Patrol SEi DAC.  I don’t care how it measures.  It makes my ears happy.
For the price around 1500$ : you can listen to the PS Nuwave, or (he is very good): Teac 501 or 505. Enjoy your music! Lukaske.
I also seriously look into the Audio Mirror Tubadour III.  It has good reviews, and it is from US.  I have bad experience in the Topping DX7 purchase.  So, I am a bit reluctant to buy from China.  I don’t know if the courier services like DHL resumes or not.  Shipping from US is a big plus.  
I’m pretty happy with Mytek Brooklyn DAC+ and Bluesound Node 2 (just for the streamer). I don’t know how the others compare and would love to do a bunch of a/b, but at least no fatigue here.
Line Magnetic LM805ia amp.