Yeah, there are many folks who are against this technique, but given that so many of us have these lying around or in our “box of a thousand cables”, it is a relatively quick and cheap way to narrow down the problem.
If you don’t want to do this, you have to try several electrical sockets. If they are on different circuits, there is also no ground noise. I by the way bought this device to get rid of the noise and this works fine as well because it is not grounded:
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Same here, did the trick for me for a very fair price!
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The solution is the same: no ground wire. So, if you have an electrical problem in your equipment where the mains voltage reaches the metal case of the device, you are not protected. Can that happen? Not easily if you have your amplifier grounded.
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I do not believe that electrical failure would damage the Dwarf. The power supply itself will of course burn out, but that the electricity is passed through to the dwarf is very unlikely from my technical understanding.
Of course, it is not possible to eliminate risks 100%; a roof tile could also fall on the dwarf or an earthquake could damage it but in my opinion the risk is bearable. 
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Huge thanks for the electromart psu tip, £9.90 later and I too am noisless! click fuzz factory active into duox…I bet my neighbours wish they could have a noisless life eh 
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perfect answer…
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I know that the topic is solved but wanted to share my solution here: I experienced a very high noise floor at home and in the rehearsal environment. The rehearsal environment was especially unacceptable. I could not imagine going on stage with that. A clean guitar sound would have needed a gate that cut off half of the sustain…
At home, I am going straight from the Mod Dwarf into an audio interface. In the other case, Mod Dwarf goes directly into a mixer. Hence, I tried a symmetric TRS cable(s) and the noise is completely gone. No DI Box whatsoever. I would even say the overall sound is better. So if this is an option for someone, try it before buying a new PSU.
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Hey napcode,
I also have a problem with high noise when plugged directly into my interface, Scarlett 2i2.
does that mean that I can buy a TRS to XLRm cable (such as https://www.amazon.com/Mogami-TRS-XLRM-06-Balanced-XLR-Male-Connectors/dp/B0002E2908) from the output and plug into my Scarlett 2i2, and it should remove any ground loop noise?
Could someone confirm if this is true for any of the three outputs for the Mod Duo X?
What would be a solution if the output only accepts unbalanced inputs, like an amp?
The 2i2 has combined jacks as well. You don’t need XLR. You can use TRS-TRS. The linked cable looks quite expensive to me (costs like 10-15 Euro in Germany).
Balanced TRS-TRS worked for me. I cannot give guarantees but give it a try. If you have something like an amp (unbalanced input, did not use one yet), you will need a DI Box or another solution.
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Could I get clarification from anyone from the Mod team whether the Mod Duo X has balanced TRS output? It seems like the headphone out is TRS, but can it be used for balanced mono output instead of unbalanced stereo output? Or are the other two outputs balanced TRS? It is not clear from the spec page.
@semmo the MOD Duo X main outputs are balanced. So, as @napcode suggested, using balanced cables is one of the common options that helps reducing ground noise issues.
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…and afaik the headphone output cannot be used as a (third) TRS output - only as a headphone output, mirroring the two TRS outputs.
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Okay, so I got a TRS cable and used it for outputting the signal from my Mod Duo X to my Scarlett 2i2. There still is noise, when there isn’t when I directly plug into my interface.
Here is with my Mod Duo X plugged into my Audio interface: Vocaroo | Online voice recorder
you can hear that there is this almost piercing kind of noise coming out of the Mod Duo X.
Meanwhile when I plug directly into my interface, I get: Vocaroo | Online voice recorder
which is practically noiseless, for my use case anyway.
I really tried everything - those ferrite beads (Ferrite bead - Wikipedia), USB isolators, and now TRS connectors, but I still have a lot of noise coming out my Mod Duo X. Is there possibly a fix somehow? I’ve been struggling with this the past year.
Certainly, it is, but we need to know a bit more about your full setup. Also, what are your input and output gain levels on the MOD Duo X?
I noticed that voltage in different places is very different, so I bought an AC automatic voltage regulator - thats the only thing that helped for my setup. Now everything is dead silent. Even my noisy tube amps.
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Setup 1:
From the same power extension, I have a Mod Duo X and amp connected. I believe the power supply for the Mod Duo X is ungrounded, as there are only 2 pins. Guitar into input 1 of the Mod Duo X using a TS cable, and output using TS/TRS (both have noise) into my amp. The input/output gain levels are all 0.00dB, I didn’t touch those at all.
Some observations:
- When I have the setup above, even with the Duo X turned off, the audio is passed to the amp, but there is still noise. Only when I unplug the power cable from the Duo X is the noise down to normal levels.
Setup 2:
Mod Duo X from the same outlet, guitar in input using TS cable into Duo X. Duo X out 1 is connected using TS/TRS (both end up having noise) to my Scarlett 2i2, connected to my Macbook, on battery/plugged in (both end up having noise). When I connect my Duo X directly into my Scarlett 2i2, there is no noise, only when I go through the Duo X.
Hope this helps in debugging the problem somehow 
. I’ve never had problems with noise issues like this when I was using other pedals, like the Zoom G1x or normal overdrive pedals, etc. It’s only been an issue for the Mod Duo X.
I see here two potential sources of issues.
1st the power strip. Have you tried not connecting to the same strip? The optimal even would be to different outlets.
2nd gain staging, depending on your setup 0dB may actually not be adequate. Hav you tried decreasing your output gain on the MOD Duo X and increasing on the amp and vice-versa?
Ok. This is weird, if it’s off the noise is being produced somewhere else. What about if you completely take the MOD Duo X out of the chain?
I didn’t get this part. Maybe a typo, but it seems that you are contradicting yourself here. Do you mean when you connect the guitar directly to the Scarlett?
If the Duo X is in the chain but not power supplied, the resulting noise level is the same as when I plug my guitar directly into the amp, not a lot of noise.
I can try these things and report back, but it would be nice if the setup wasn’t so complicated, especially I want to bring it to different venues. I have a feeling that the second suggestion might make it worse, since the noise level seems to be independent of the output level of the Duo X. I’m not sure why this issue is so prevalent for the Duo X and not my other devices.
Ah sorry, that was a typo, the first ‘Duo X’ should be ‘guitar’. When I plug in my guitar straight into the Scarlett 2i2 it is noiseless. When I plug my guitar into my Duo X and then the Scarlett 2i2, there is significant noise which I can’t remove.