I have this card currently paired with an HD650 and regarding to the overall sound quality it’s top notch, however I found some bugs and issues that are worrying me right now, which I don’t think is related to its drivers but the operating system most likely.
 
First bug I found when listening for the first time to my music is that when I installed the EVGA NU Audio software it came by default set at 24/48 so I didn’t bother looking into the Windows sound settings to check if it’s also set there at the exact same values. Well, resulted that it was actually set at 32/48 there so the music was experiencing some weird conversion which made the songs sound very harsh and less detailed which disappointed me at first glance. Seems that if you set any sample rate in the EVGA software, the Windows sound settings will keep the last bit depth previously selected, for instance, if you are currently at 24/48 in the EVGA software and you switch to 16/44.1, in Windows’ sound settings this change will appear as 24/44.1 and you have to change it manually to 16/44.1.
 
Second bug I have experienced, and it’s of an issue, is that when I browse heavily either on Chrome or Windows when listening at the same time to music, there are very short delays or intererences (like 0.1sec) which annoys me quite a bit. My theory is that the SSD when doing random reads/writes is the causant since W10 is not the most optimized OS. Another thing I have to mention, it was much more noticeable when my EVGA software configuration was 100% Master Volume and 50% Headphone than 28% Master Volume and 100% Headphone. This last config also sounds a lot fuller and detailed to me, both in music and games during my testing.
 
The third one I found was related to foobar2000 when I changed from DS to WASAPI (event). Songs sounded more ''neutral'' and less ''fun'' to me, like it lost some punch.
 
I am currently running on Windows 1809, build 17763.678 (no fresh install), the card is running on a PCIe gen 2/x16 slot since the gen 2/x1 slot is covered by the GPU heatsink and the other gen3/x16 is too close to the fans of the GPU (I have a Z97 Gryphon, mATX build). I also have plugged an original EVGA G2 750W SATA power cable (which comes with 3 extensions) that goes into the sound card to the ''SATA 3'' PSU port for an easier access during the installation. I already have a SATA power cable connected to my SSD (Samsung 850 EVO) on the ''SATA 1'' PSU port and I didn’t wanna use one of the 2 heads remaining in case there were ''powering issues'' for sharing the same cable both SSD and NU Audio card, plus those might have some dust on the pins since I have this PC for almost 4 years.
 
EDIT: After a lot more listening I came to the conclusion that it’s ideal to leave the Master Volume to 100% as recommended and ajust the Headphones volume to a reasonable amout for you to hear without getting fatigued (in my case with the HD650 is 64% and 72% the max I can stand depending on the music genre/recording). I’ve noticed that if you leave the Headphones volume to 100% and you ajust the Master Volume to let’s say 28%, your headphones won’t receive all the power needed and will result that one of the cups (the right one in my case) has more power than the left one and you will lose quite a bit of detail too.