M4 and headphones question

[micihch]

Just got a new M4 and I had the problem of distorted sound as described by quite a few users all over the internet.
It turned out to be the headphones in my case...

The problem I had was that audio from VIs was distorted at any level and sampling frequency, but system audio not.
I suspected the cabling and tried all sorts of adapters, cables etc pp.

In the end, I'm not sure, but I guess..., it was the headphone impedance. At least it now works if I use my old AKG 271 with 55Ohm. Before I used my Beyerdynamic DT880 with 32Ohm. The later were probably overloaded by the headphone amp?

What's strange to me is that system audio from e.g. youtube videos was never distorted with the Beyers, only audio played from VIs (VSL synchron pianos and Pianoteq in my case).
Swap he headphones and no distortion anymore, and no dependency on cables, works with any cable/adapter.

The Beyerdynamics didn't have this problem with the Ultralite mk3 I was replacing.

Do I miss some obvious explanation or is it really just that you can't use too low impedance headphones with the M4?
But even if this is the case, why was system audio through the M4 not distorted?

I'm on a MacBook Pro M1 14' with Sonoma, latest version.

[mikehalloran]

The rated impedance of the SONY MDR-7506 'phones is 63Ω and I've never experienced the distortion that you describe.

I'm not saying that there isn't a problem but I'm guessing that low impedance isn't it. You have a number of monitoring options. I would double-check the manual. Pay attention to the Input Monitor Mix—in the middle position, you will get phase distortion from combining the Input/Output — it cannot be 50/50. (near zero latency≠zero latency).
https://cdn-data.motu.com/manuals/usb-c ... _Guide.pdf

Have you asked MOTU about this?

A few sites have opined that the M4 doesn't like high impedance but they never publish data to back this up.

An easy way to test is to use a headphone amp. The only inexpensive unit I like is the $40 Mackie HM-4 but I really like it. You will also need a TRS cable. Anyway, this should settle the issue of whether it's the M4 or something in your setup.


Otherwise, as the song implies, I think we need more info.

[micihch]

Thanks Mike!

Well, further investigation led me to the conclusion that it's the jack/cable of the headphone.
I screwed on a 6.3 mm adapter from another headphone and bingo, the DT880 works again without distortion.

Well, that was strange, especially the thing about no distortion form youtube but from the M4.
Anyway problem solved, I guess. And: it's not always the software that's at fault, lol.
(And I hate these minijack to jack screw-on adapters even more.)