M2: low headphone output

[NigelOwens]

New M2 user here. I just received my MOTU M2 yesterday. I connected it to one of the M1 Mac Mini's USB 3.1 bus connections (via an Apple USB-C cable), installed the MacOS driver (wouldn't see the device without it), and updated the firmware. After which the device appeared on the USB bus and in GarageBand. All good there.

I'm noticing that the headphone output is kind of low with my DT770 250 ohm headphones, and I really need to crank the headphone volume up. With my input signals running so that they peak in the red/top of the yellow segments, I have to turn the headphone amp up to the 2 o'clock to 3 o'clock position to get decent output. For comparison, the same phones connected directly to my synth are reasonably loud at 2/10 (two tenths of the output scale). I also tested with a pair of consumer grade low impedance headphones, with identical results.

Everything else seems happy. The monitor speakers are getting a good feed at 10 o'clock.

Is this normal for the M2, or am I doing something incorrectly?

[mikehalloran]

A low impedance headphone like the SONY MDR 7506 (63Ω) will be a lot louder in most interfaces than yours at 250Ω. Here’s some more info.

https://blog.zzounds.com/2021/09/01/he ... explained/

This is an excellent $40 headphone amp that will give you additional headroom. (1/4” TRS–TRS cable not included).

The M2/4/6 supports Core Audio on the Mac. Drivers are not required for a Mac unless you want to enable the Loopback functionality.
https://cdn-data.motu.com/manuals/usb- ... _Guide.pdf

[NigelOwens]

Thanks for responding. As I wrote, a low impedance headset had the same result. In general, I don’t find much difference in volume levels between the 250 ohm and 8 ohm headsets with my devices. And I expect a good quality piece of gear to be capable of driving high impedance phone’s adequately.

As for the drivers, the M2 did not appear as a device until I installed the drivers.