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[dcozmonaut]

I just purchased the following system and set up the following system last weekend:

4th Gen Intel Core i5-4250U NUC BOXD54250WYKH1 Silver with Black Top
240 GB Samsung EVO SSD
Audioquest Dragonfly 1.2 USB
USB Wired Mouse (cheap Amazon)
USB Wired Keyboard

I'll go into some details below in the hopes that someone might have a suggestion for me, but is anyone else having noise issues with the NUC?  I am going to return the system otherwise, which is unfortunate as I thought this would be my new media pc.

I installed Windows 8.1 and could hear noise/buzzing when I either moved windows around on the screen or used the mouse scroll button.  This occurred even after updating the system (via Windows update).  I also tried CentOS 7 (noisy) and then Lubuntu (only through a live usb) which actually worked fine.  Even stranger is that at some point I went back to the Win 8.1 installation and the sound was fine.  I wrote it off as the OS simply needing an update.  But after a couple of reboots the noise problems returned.  I was going to blame the dragonfly since there have been reports of similar noise issues with Windows (only 8 though), but just to be sure I plugged that into my old AMD mATX desktop computer.  On my older computer the dragonfly is nice and quiet (I also used the same cheap mouse/keyboard in case that was the noise source).  Therefore, I have to conclude the NUC USB is causing the noise. 

Again, thanks for any ideas or suggestions.

[mwillems]

I have almost the same NUC as you and have a suggestion.

USB 3 ports are known to generate interference and/or electrical noise, see e.g. http://www.intel.com/content/www/us/en/io/universal-serial-bus/usb3-frequency-interference-paper.html.  It's in a bandwidth (2.4 GHz) that shouldn't be an issue for a DAC (although I can attest that it will wreck the performance of a bluetooth keyboard).  However, several people on the forums have experienced strange behavior with DACs plugged directly into a USB3 port.  The issue is worst when the device is a dongle style device that plugs directly into the port (because the RF interference is localized at the port). 

An easy diagnostic test to try: grab a short (6 inches should work) USB extender cable (or a USB 2.0 hub) and plug your dragonfly into the extender/hub as far away from the NUC as you can manage.  If the problem improves or resolves, then you know it's almost certainly USB3 interference.  If it's exactly the same, it's probably another issue.

Several forum members solved USB3 DAC issues by plugging into a hub as described, and I resolved serious problems with several bluetooth devices using a 6 inch extender cable.  It may not be a fix for you, but it's worth a shot.

[dcozmonaut]

I actually tried a USB 2.0 hub an hour after I posted this question and had identical results.  My Apple Time Machine is next to the PC so I will try moving it and/or the PC to see what effect, if any, it has.  I also plugged the Dragonfly into my macbook and it worked perfectly.  I will experiment a bit more this evening and see if I can reduce or eliminate the noise.  Thanks for the reply!

[JimH]

You've probably considered other sources of the noise.  Wireless network, microwave oven, etc.

Hums are often related to lack of a good ground, but now I'm out of my comfort zone.

[astromo]

I know it's another manufacturer but I suspect some of the advice here is generic:
http://audioenginefiles.com/pdfs/Whitepaper.pdf

[Hilton]

The Intel NUCs don't have very good power filtering and you may have a ground loop issue.
Try plugging the NUC directly into a power socket that isn't shared with anything else, try a few sockets around the house.
Sometimes you'll be surprised what you hear between one power socket and the other if its noise on your house power circuits.

Also try both USB ports on the back and unplug everything except the DAC and see if the noise disappears.
PS. Also unplug HDMI or any other connections except for the DAC.

[InflatableMouse]

If you have a dimmer or LED lights in that room (or even on the same electric group) try switching them all off.

I have a bunch of dimmed LED lights in my room and when I turn them on I can hear a hum on my headphones. It shortly peaks every time I touch the dimmer. When I turn the lights off, its gone.

[dtb300]

I have the same NUC and  have connected USB in three different configurations:  

iFi USB Power -OR- Schiit Decrapifier to either an iFi iDSD DAC, -OR- Wadia 121 DAC and do not have the noise issue you describe with any configuration of the items I listed.

Now I am running W2012R2 for an OS (GUI or Core mode), with Phil's AO, and my music is on an external USB drive hooked up to the NUC.   I usually run the DAC out the front ports and the drive out the back ports.  And my NUC and drive are run off their own LPS.

[dcozmonaut]

Thanks again for the additional posts.  I tried two different usb hubs, shutting off lights, shutting off the monitor, and a second mouse, all with no change.  Moving the mouse, especially the scroll wheel, seems to generate the most noise, so my conclusion (based on limited knowledge, experimentation, time, and equipment) is that the source of the noise must be the usb 3.0 hub on the NUC, and the dragonfly simply does not have enough filtering and/or isolation to compensate.

I am leaning towards returning the NUC because of this and the fact that it is not that much quieter than my existing setup (mATX in Antec NSK2480 with PCI audiophile 2496).

[InflatableMouse]

Can you try with a non-USB powered DAC? One that has its own PSU?

I am using the same NUC with a Teac UD-501 DAC and I don't have these problems, on none of the USB ports.

[6233638]

Are all devices connected to the same power outlet?
Obviously doesn't apply if it's just the NUC and a pair of headphones directly connected to the Dragonfly.

[astromo]

I know this post is a little old but I had a rice bubbles experience (i.e. snap, crackle and pop!) with my audio set up at work (MC20 portable via an Audio Engine D1 24-bit DAC. Thought I'd share here in case others follow a similar path.

I'd mentioned a USB isolator over here:
http://yabb.jriver.com/interact/index.php?topic=91483.msg630725#msg630725
here's a thread from CA:
ADuM4160 - powered USB isolator?
but it looks pretty ugly. Retro-industrial may be a fashion look but I prefer something with a bit more refinement.

I did a bit of digging on the interweb and found a unit with a case and a connecting cable (see pic) on eBay advertised as:

HiFimeDIY USB Isolator ADUM4160, 5KV/1KV signal/voltage isolation, DC-DC convert

by a store with the tag eastern_technology. Please note that the unit has its limitations:

Will it work with my DAC?
It works with DACs that support up to 96Khz/24bit, it does not work with 192Khz/24bit sample rates because they require USB High Speed 480Mbit/s.
Also, some DACs requires more than 200mA power. This might be if they have a headphone amplifier, or a MCU that draws more power.

It was a little slow in arriving but it turned up and solved my noise problem at work. I didn't get to test in on my Dragonfly USB DAC but I'll give that a go when I get the chance.