RME ADI-2 DAC FS & MP145 IEM Weirdness

[Crook]

Anyway, first world problems.

Love my DAC FS, hands down best piece of electronics I own. Line out silent, phones silent, IEM output noisy (or so I thought).
Using my Hidizs MP145 IEM with the RME and I have ground loop noise I believe. If I place my hand on the DAC, or touch the 3.5mm plug it falls silent, remove it I have a low level buzz.
Now I've heard it, I can't not hear it.

Removed the MP145 from the DAC FS and inserted 7hz Zero 2 and I have silence.
Use the MP145 on the Fosi DS2 dongle and I have silence.
I swapped cables, 7hz silent on any cable, MP145 has noise on any cable.

So my issue is very specific. I get ground loop noise on the MP145 and DAC FS combination and every other combination I've tried is silent.
Obvious way to solve this is to not use the MP145 on the RME, but I'd really like to.

Any ideas?

 

[respice finem]

My idea would be to post the question here:

ADI-2 & 2/4 Pro series, ADI-2 DAC series (Page 1) — RME User Forum

ADI-2 & 2/4 Pro series, ADI-2 DAC series (Page 1) — RME User Forum —

forum.rme-audio.de

 

[staticV3]

Classic case of mains leakage current.

Other examples:

A

Post in thread 'Topping DX1 mini desktop DAC & AMP'

Jun 2, 2025

My unit has subtle but annoying hum, sounds like 50 Hz (the mains frequency here). The hum can get slightly louder or quieter as I move on my chair, and it disappears if I put my finger on the DX1's case, or on any metal part of my PC case. I don't have the third earth wire in my apartment, only L+N. Would this be solved by a USB isolation device? And do you think this could be a defect? I think it developed slowly over time and wasn't an issue for the 1st year of using the DX1. Now it's at ~2.5 years. But it's also possible, even if unlikely, that I just haven't noticed it before.
This...

• Alexium

C

'Electrical noise through headphones while touching phone'

Mar 25, 2025

Hi everyone.

I'm not sure what exactly to call this problem.
Everything of mine is connected to the same power bar which is connected to one socket in the wall. Headphones -> RME DAC -> powerbar
Everything works as expected, but when I touch my phone (while its charging) or my heating pad with my headphones on or anything else with an electrical current in it, i will proceed to hear a pulsing electrical noise in my headphones (planar magnetic).

I seem to have tried everything and nothing works except when I use my set up with my macbook while it was not charging into the wall, i heard no...

• chives

'Earth hum from headphone amp.'

Feb 13, 2025

Hi audio scientists,

I've been trying to eliminate a ground hum from my desktop system, audible only when I use sensitive iems. I bet someone here knows exactly what to do.

I've systematically removed as many components as possible and narrowed it to the headphone amp -- a Sabaj A10h.

With nothing connected to the line input, but the unit plugged in, and IEMs connected and in my ears, if I move about in my office chair or stand up I can often hear an earth hum. I can eliminate it by touching the 6.35 -> 3.5 jack converter connected to the audio output of the amp. This still happens even...

• vext01
• ground loop interference noise
• Replies: 7
• Forum: Audio Electronics and Hardware

S

'Yet another weird ground loop issue, and I thought I had left these stupid things behind'

Dec 13, 2024

So my bedside setup had been a Mac mini, topping dx3, and a little topping headphone amp, all running unbalanced. but I started getting a low-level hum that disappeared if I touched a case or unplugged the Mac mini. I ruled out the USB connection. The Mac mini was a 2012.

In the course of troubleshooting, the old Mac mini got much worse! Really loud buzzing. So I threw that shit away and got a new, dinky Mac mini. Pretty cool.

Low-level hum persists. So I pull out a Topping DX7 combo DAC/amp that had been mothballed owing intermittent weird screeching in the signal. No more hum. Since...

• suttondesign
• Replies: 19
• Forum: General Audio Discussions

Try plugging out all cables from the RME except the power supply and the MP145.
Does it still hum?

If the hum is gone, then your PC is likely the culprit.
To fix it, connect to your PC via Optical instead, or add a USB isolator.

This one is recommended by RME:
[https://www.audiosciencereview.com/forum/index.php?threads/topping-hs02-coming.41614/post-2078966

 

[respice finem]

I've had a USB "chirp" problem and indeed a USB isolator between the PC and the ADI2-DAC solved it:

DSD TECH SH-G01B Izolator USB z szybkim chipem ADI ADUM3165-480 Mb/s : Amazon.pl: Elektronika

DSD TECH SH-G01B Izolator USB z szybkim chipem ADI ADUM3165-480 Mb/s : Amazon.pl: Elektronika

www.amazon.pl

 

[Crook]

I'll try this tonight. I don't have any USB connections. To the RME I have optical from Wiim mini (optical only) and coax/rca from minidsp pocket ADC, that converts my turntable output, so I can room EQ both sides in the DAC. Another solution might be swap the mini for a pro and use the coax/rca from the Wiim and switch to optical from the pocket ADC. I assume the noise can't travel from the analogue side to DAC over optical?

 

[staticV3]

I assume the noise can't travel from the analogue side to DAC over optical?

Correct.

If you plug out everything but power supply and MP145 and the hum is still there, then the issue likely comes from the power supply.

You can try grounding the ADI-2 housing manually, or if that doesn't work, you may want to consider RME's power supply filter or upgraded power supply

Edit:
If the hum disappears with the PocketADC, then you can keep the WiiM Mini and connect both using a Cooidea Toslink switch:

 

[Crook]

Correct.

If you plug out everything but power supply and MP145 and the hum is still there, then the issue likely comes from the power supply.

You can try grounding the ADI-2 housing manually, or if that doesn't work, you may want to consider RME's power supply filter or upgraded power supply

Edit:
If the hum disappears with the PocketADC, then you can keep the WiiM Mini and connect both using a Cooidea Toslink switch:
View attachment 469963

Thanks. Plenty for me to be going at there. 1st job, see if it's the RME supply. I've also had success in the past running wires case to case, so a few things to try before spending any money I think. Thank you.

 

[Crook]

Ok. Everything disconnected apart from power and mains buzz is there. What I don't understand is why it only happens with mp145. I removed the mp145 and inserted zero 2 and total silence, inserted 2 other sets of buds Samsung and Apple and total silence. 2 different phones total silence. Ear to tweeter when all connected up on both opt and coax, again total silence. I looked at RME filters and power supply and anywhere between 50% and 100% cost of the dac! I'll run a wire this weekend from ADI to other cases to see if I can resolve, but surely if everything else is total silence including other IEM apart from mp145, I can only logically conclude it's the MP145 and not the dac? If I can't resolve I'll just use the mp145 mobile and not on the dac.

 

[staticV3]

What I don't understand is why it only happens with mp145

A plastic IEM housing isolates and disrupts the leakage current.

Metal housings conduct the current and enable it to flow through your body back into GND. On the way, the leakage current excites the IEM driver and makes it hum.

If you sit in your chair, take your feet off the ground and make sure you're not touching any metal, then the hum should disappear even with the MP145.