Is your USB hub AC adapter powered or USB port powered? If it's USB port powered you could try a cheap AC powered USB hub or buy a USB isolator to fix the ground loop issue. If you don't have an optical out port then you'll have to google for how to check for ground loop issue and how to fix them if possible because that's the most likely possibility, especially if you managed to reduce most of the hiss/pop by inserting a USB hub in the chain. That's how I run mine, onboard Realtek (SPDIF out)> (SPDIF in) D1 (RCA out)> (RCA in) Asgard 2 (6.3mm out) > Headphones. Just use the D1 USB for power via motherboard or USB AC adapter.

Have you tried the front and back USB ports in case it's a ground loop issue? Do you have a SPDIF optical out jack on your motherboard? If so, you can pipe the music out through that and feed the D1 via clean optical signal. However, there is a quick random stutter and quiet pop randomly (not in the source files)

I plugged the DAC into a USB hub and the hissing/popping is gone. Same thing happened on a clean Windows 7 64 bit install, no AV and no sound card drivers. M1K3Z0R wrote: ↑EDIT: Looks like an electrical issue.

Audioengine d1 dac 24bits