Static noise help please


Recently just notice Static, hiss, popping sound(I don’t think I hear that before but I might be wrong) from both speakers when volume alway down with music off. Happen only when connected usb from iMac to Schitt Modi 2 Uber DAC. Static noise disappear after unplug either end of the usb. I am using temporally cheap 15 feet usb a/b cable. Pre amp is ARC LS7,ARC VS60 amp,and Sonus Faber Venere 2.5.  Any advise?
I swap from ARC setup above to Cary SLI80 interested amp and used the same usb cable and the static noise was gone. So I think it is not the usb cable problem. Is that possible static noise come from tubes?

Regards,
Eddy

eddy1
After been reading so many posts and many searched, my conclusion is Dirty power (5V) from computer to the USB.  So my plan was going to cutout 5V +(Vcc) and -(Ground) cables from USB and will only run Data to DAC but found out that all Schiit needed 5V from USB.  
Eddy, now you are getting to next level in computer audio learning. Yes, noise from computer passed to dac via usb is a HUGE problem. That's why Schitt makes Wyrd(which I use), even better according to many is Uptone Regen. Other things like iFi cable with separate power and signal legs all are trying to deal with this problem. Computers are noisy, since they usually are running many processes all generating noise. Many audio software programs, try to get the computer to turn off other processing to quiet down the computer so less noise goes to the usb/dac. 
IMHO the most exciting development is the newer ethernet streamers that let you replace your computer with a small low power low noise linux box and stream your library from a network attached storage (NAS) drive located in another room and attached by ethernet cable only. 
This is a rapidly changing corner of the audio world. IMHO, Sonore, Uptone, Aurender and other companies moving in this direction are leading where digital high end music is evolving. Cheers,
Spencer
Eddie - I'm guessing you will be wanting to try a "double-headed" USB cable that separates signal from power.  The one from iFi (Gemini Dual Headed USB cable $265 for 1.5M on Amazon) is kind of pricey, I think.  There are some lower cost options.  

I bought one from a seller on Ebay [Doukmall (China)].  At the time it was only $59.  I use it with an inexpensive Enercell 5V AC/USB converter.  No noise and things sound great.

Here's a link to the latest from Doukmall.
http://www.ebay.com/itm/SLK-Audio-OCC-Copper-USB-Audio-Cable-signal-wire-Hifi-Decode-Line-50CM-/252022624130?hash=item3aadb80f82

Looks like the price has gone up but still cheaper than the iFi.  If you are skeptical about the quality of the power from the Enercell you can try the Wyrd from Schiit.

Here on A'gon there is a seller robpriore who sometimes lists a "USB Disruptor".  It is also a double-headed USB cable but he sells it with a power supply and the price was previously only $74 or so.  I don't see it currently listed in the usual Digital/DA Converters category so you might want to drop him a note and inquire about current availability.  

Here's a link to a discussion about it:

https://forum.audiogon.com/discussions/audio-grade-usb-cables/post?highlight=usb%2Bdisrupter&pos...

Hope this is of use.  Good luck.
Spencer, ghosthouse,  Thank you.  I think I will do double headed USB cable myself.  I have USB certified 10 feet and 6 feet coming so I will give it a try.  But will try with 5V DC (http://www.amazon.com/Sony-CPV3-2800mAh-Portable-Supply/dp/B00FAJYO58) first then will order wall plug Emercell.

Eddie - do you already have that Sony portable power supply?  I'm just wondering how long it will last in an audio application.   You could also just try using a typical wall plug/USB converter like for charging an iPone...or even a powered USB hub, for that matter.  

Whatever you decide, good luck cleaning up that static.