Mad Scientist IC’s

@renisnceman - the Node 2 is not a grounded unit- it only has a two pin plug and is known for creating hum with some amps.

I have the Node 2i and if I disconnect my phono stage the hum is present. My phono stage is correctly grounded and when connected it eliminates the hum.

The carbon fibre probably helps eliminate the hum by providing a lower resistance neutral pathway between components.

Grounding one of the RCA sockets on the Node 2 would probably fix the issue if required

Regards - Steve.

@williewonka the dac is the Jolida dsd non- bluetooth version connected to a Bluesound Node 2 via a Nordost Silver Shadow digital cable with bnc-rca adapters.  Speaker cables are diy silver over copper ribbon 10 AWG with cable lifters.  The hum is not the typical 50/60 Hz- higher in frequency and it increases as the volume control increases on the dac.  Power cables for the dac and Node are Cullen and Transparent for the amp.  Thing is, without changing anything, except for switching back and forth between the Dueland-Schroeder IC’s and the Mad Scientist IC’s, the Mad Scientist are dead quiet and the Schroeder’s hum.  Tapping the Schroeder’s doesn’t add to the hum, but moving them around tends to alter it. The good thing is the MS sound better, but I’m curious as to why they’re silent. At this point it’s more an intellectual exercise, but I wonder if the carbon fiber for the signal conductor in the MS cables has something to do with it.

@renisnceman - WRT the hum
1. is the hum a 50/60 Hz mains hum? or is it higher or lower in frequency
2. is the hum a constant level?
3. or does it get louder as the volume is increased?
4. what speaker cables are you using?

Which model Jolida DAC do you have?

I see the STA200 is a power amp
- so I assume you are controlling the volume via the DAC - correct?

The microphonic effect - e.g. The cable from my turntable suffers a microphonic effect.
- i.e. I can hear sound if I tap the cable with my fingernail
- does this happen in your case?
- this can cause hum if in close proximity to other cables

Is the cable in question near a power cable or a component power supply?

One last thing to try - using a piece of wire, touch one end to the neutral side of the RCA socket the cable is plugged into and the other end to a "common ground point"
- does the hum go away?
- if yes, it may be because of the grounding design of the attached components and the geometry of one of the cables highlights this anomaly

Also, Cables can cause issues within attached components and sometimes it is another cable (e.g. speaker cables) in the system that causes the problem
- answers to all questions above will help get to the "root cause" of this problem

Regards - Steve

It's obviously the different RCA plugs used by each; it couldn't be anything else.....................

Speakers hum with the Schroeder- Dueland IC’s; they don’t hum with the Mad Scientist IC’s.  No other changes to the system.  

Of all the many things it could be you assume its this one in particular. Why?