I have the Audio-gd R8 DAC and its a superb DAC for the money. You also have many setting options on the front panel and its FPGA programable wich can upgrade its sound with new firmwares that they launch about twice a year.
Ive heard three systems much more expensives than mine (just the DACs costed about 15/20k) and I prefered the sound of mine by far. Of course the whole system is important, but the R8 played its role with authority.
A couple of advices:
1-If you use USB from computer, upgrading your digital rig with an audiophile switch plus (like the Uptone Etherregen) a dedicated streamer (like the SOtM SMS-200 Ultra Neo) plus a good DDC (I have the Audio-gd DI-20) will upgrade the sound quality of your DAC to a compete with ones costing many more times.
2-Dont pay attention to measurements, just your ears. My Line Magnetic LM-508IA 300B 805 valve amp has about 1% of total THD and my NC500 based class D amp (well regarded among audiophiles) has about 0.001% of THD. I prefer by a WIDE margin the LM-508IA, its a music monster. Much more realism, body, 3D sound and tone. Numbers are just that. You cannot guess the taste of a food for its calories.
Finally, you can read a good review of the R8 here: https://www.hifi-advice.com/blog/review/digital-reviews/spdif-dac-reviews/audio-gd-part3/
In this review the used the older version of the R8. Now it has new DA boards and new firmware that rise the sound quality considerably.
Ive heard three systems much more expensives than mine (just the DACs costed about 15/20k) and I prefered the sound of mine by far. Of course the whole system is important, but the R8 played its role with authority.
A couple of advices:
1-If you use USB from computer, upgrading your digital rig with an audiophile switch plus (like the Uptone Etherregen) a dedicated streamer (like the SOtM SMS-200 Ultra Neo) plus a good DDC (I have the Audio-gd DI-20) will upgrade the sound quality of your DAC to a compete with ones costing many more times.
2-Dont pay attention to measurements, just your ears. My Line Magnetic LM-508IA 300B 805 valve amp has about 1% of total THD and my NC500 based class D amp (well regarded among audiophiles) has about 0.001% of THD. I prefer by a WIDE margin the LM-508IA, its a music monster. Much more realism, body, 3D sound and tone. Numbers are just that. You cannot guess the taste of a food for its calories.
Finally, you can read a good review of the R8 here: https://www.hifi-advice.com/blog/review/digital-reviews/spdif-dac-reviews/audio-gd-part3/
In this review the used the older version of the R8. Now it has new DA boards and new firmware that rise the sound quality considerably.