buzzing buzz

[Johnman1116]

I have the Bottlehead Crack with no Speedball. Tubes should be burned in by now.....
I am getting this moderately high pitched buzzing. Its not constant and flickers and fades. Changes with the volume control
sounds like.. ttttttttttt

Desktop -> Odac or Audioengine D1 -> Crack or Audioengine A2
Ive tested different usb ports, switched out speakers and headphones, Dacs.
Actually I just realized that the only thing I hadnt changed is the cable but I cant because they use different connectors.
Also the cable for the Odac has a Ferrite choke and the D1 doesnt. Cant seem to find a USB type A type B with a ferrite choke.. and I dont have another one to swap out.

Could this be the answer? I kinda assumed it was a tube problem..

[Doc B.]

Short the inputs and see if the noise goes away. If it does it is from something ahead of the Crack, cables or source component.

[Johnman1116]

So basically anything like:
http://www.siteswithstyle.com/VoltSecond/Shorting_plug_rca/shorting_plug.html
which is http://www.takefiveaudio.com/mall/shopcontent.asp?type=RCA_Input_shorting_plugs
and
http://www.mcmelectronics.com/product/27-5335&cid=prodKeyWord
 
Sorry just to clarify. I see that a 75 ohm resistor is preferred for digital inputs but what resistor is preferred for the Crack?
none of the shorting plugs i found posted what resistance they used.

[Paul Birkeland]

A short is zero ohms.

[Grainger49]

If you have alligator clip jumpers you just jump the center conductor of the RCA jacks to the outer conductor.  If you don't have any of these you should buy some.  They are very handy for all kinds of things like clipping your black lead to the chassis/ground.

[Johnman1116]

so you want me to short the inputs on the Crack with 0 ohms.
by plugging in rca's and alligator clipping it?

Trying to make sure everything is clear.
Thanks

[Grainger49]

There is the thread about making shorting plugs in Tech Tools.  VoltSecond mentions that a dead short can be a dangerous thing and suggests a resistor load.  Not in the case of input checking

I suggested alligator clip jumpers as an alternative.

If you have shorting plugs you can use them.  If you have alligator jumpers they will save you a trip to Radio Shack for the parts.

But you need to try this step to see if the source of noise is in the Crack or outside the crack.  To be fair to your crack turn off all other components within 4 feet of the Crack, short the inputs and listen.

[Doc B.]

I seem to have to reiterte every once in a while that a dead short across the input is what you want for the test we are suggesting. Worrying about putting a resistor across the plug is for loading outputs.

[Johnman1116]

Dead Silent.

Someone mentioned ground loops, ground lifts and audio isolation transformers. I thought plugging everything into one surge protector solved the dreaded ground loop issue, more or less...
The buzzing is present as long as the D1 is on, even if its not being used. Buzz is gone after i unplug usb (which is also the power and digital input).

I swapped out the Crack for a Cmoy and there is no buzzing. Cmoy is using ac adapter and same outlet.
Which now makes me think its the Crack again but it was silent with the ODAC....