Motu M2 Review (Audio Interface)

[AnalogSteph]

I'm changing my cables to XLR btw, for safety.

Something like these is what you want then:

Cordial CFM 1,5 MV

Audio Cable Connectors: Balanced male jack to male XLR, Cable Cross-section: 2 x 0.20 mm², With Neutrik Rean connectors, Gold-plated contacts, Casing: Black metal, Hand-soldered, Length: 1.5 m

www.thomann.de

(I'm using some of those myself.)

So to clear up the confusion, I guess your current instrument cables look like these?

Cordial CFU 1,5 PP

Professional Twin Audio Cable 2 x Jack male to 2 x Jack male, Cable cross-section: 1 x 0.22 mm², With Neutrik (Rean) connectors, Hand-soldered with gold plated contacts, Length: 1.5 m, Twin cable, Colour Coded

www.thomann.de

This is 1/4" TS. That would explain why the M2 output is unhappy then, basically half the output stage is shorted to ground.

 

[Exopowk]

Something like these is what you want then:

Cordial CFM 1,5 MV

Audio Cable Connectors: Balanced male jack to male XLR, Cable Cross-section: 2 x 0.20 mm², With Neutrik Rean connectors, Gold-plated contacts, Casing: Black metal, Hand-soldered, Length: 1.5 m

www.thomann.de

(I'm using some of those myself.)

So to clear up the confusion, I guess your current instrument cables look like these?

Cordial CFU 1,5 PP

Professional Twin Audio Cable 2 x Jack male to 2 x Jack male, Cable cross-section: 1 x 0.22 mm², With Neutrik (Rean) connectors, Hand-soldered with gold plated contacts, Length: 1.5 m, Twin cable, Colour Coded

www.thomann.de

This is 1/4" TS. That would explain why the M2 output is unhappy then, basically half the output stage is shorted to ground.

I literally bought those ones you recommended me, previously I had two of the Roland RCC-5-TRTR.

 

[AnalogSteph]

I literally bought those ones you recommended me, previously I had two of the Roland RCC-5-TRTR.

Hmm. Those are TRS to TRS cables, I wouldn't expect any issues with them. So don't be too surprised if the new cables don't help. In which case, however, I'd be scratching my head again about the cause of your problem. The limiting factor should be the power amp or woofer in your HS5s, long before the M2 output is at its limits (unless defective, of course).

 

[Exopowk]

Hmm. Those are TRS to TRS cables, I wouldn't expect any issues with them. So don't be too surprised if the new cables don't help. In which case, however, I'd be scratching my head again about the cause of your problem. The limiting factor should be the power amp or woofer in your HS5s, long before the M2 output is at its limits (unless defective, of course).

Surely, I am aware. With that said, how should I troubleshoot where's the problem coming from? I tried changing the speaker level and it seems to hit at the same volume, but again, could be an issue from the source sound or the DACs. Is there any DAC distortion comparison?

 

[Krusty09]

Does anyone know if you can simultaneously take in line level audio but playback different line level audio at the same time?

Thanks

 

[AnalogSteph]

Does anyone know if you can simultaneously take in line level audio but playback different line level audio at the same time?

I imagine those musicians trying to record to a click track or backing track would be rather miffed if full duplex operation didn't work, and you'd find numerous complaints to that effect. Different sample rates might still be an issue, but if in doubt you can ask MOTU about that one.

 

[bequietjk]

Coming back to say there is plenty of juice for the DT 700 Pro X. Yeah its only like what, 20-50mw maybe? But it's working well enough for these cans and my application until I grab a A70 or A90D.

 

[staticV3]

Coming back to say there is plenty of juice for the DT 700 Pro X. Yeah its only like what, 20-50mw maybe? But it's working well enough for these cans and my application until I grab a A70 or A90D.

The 700 Pro X has an impedance of 48Ω.
At 48Ω, the Motu M2 can output about 1.1V, or 25mW.
According to Beyerdynamic, that's enough to drive the 700 Pro X to 115dB SPL Peak.

That's extremely loud (more than 10x as loud as my usual listening volume, just as an example).

For the 700 Pro X, an A70 or A90D would be comically overkill and wouldn't actually give you better sound quality.
Unless you're planning on getting some seriously challenging headphones that can make use of an external Amp, I would hold off on that purchase.

 

[bequietjk]

The 700 Pro X has an impedance of 48Ω.
At 48Ω, the Motu M2 can output about 1.1V, or 25mW.
According to Beyerdynamic, that's enough to drive the 700 Pro X to 115dB SPL Peak.

That's extremely loud (more than 10x as loud as my usual listening volume, just as an example).

For the 700 Pro X, an A70 or A90D would be comically overkill and wouldn't actually give you better sound quality.
Unless you're planning on getting some seriously challenging headphones that can make use of an external Amp, I would hold off on that purchase.

After I posted this and have had time to listen, yep, you're right. Here on the Motu M2 I keep it at 9-10 o' clock on the volume knob and it is definitely plenty. I suppose I was referring more to a better measuring headphone amplifier in general and not necessarily for more power. And for the future, I plan to get some high impedence and planar headphones so something like the A90D or A70 should do good.

 

[rhcaldwell]

This is a review and detailed measurements of the Motu M2 Audio Interface (DAC, ADC and headphone amplifier). It is on kind loan from a local member and costs US $179. I previously reviewed Motu M4 which is its larger brother.

The M2 has the look of other Motu products:

View attachment 109298

I like the color LED bar graphs as if you don't get sound, you know whether it is or is not getting to the product. Front panel sockets are for input sans the 1/4 headphone jack. The back has the only set of outputs (both balanced TRS and RCA):

View attachment 109299

The overall feel of the product was good. Compatibility was great without me having to use their control panel or driver except to set the ADC sample rate as needed.

M2 is bus powered using that USB-C connector which was nice.

Motu M2 Measurements: DAC
Measurements of the M2 started on a sour note using the unbalanced output with one channel being 8 dB worse than the other due to noise. Strangely, as it sat there for a few minutes, the noise subsided fair bit and improved that channel to 104 dB SINAD:
View attachment 109300

Fortunately there was no such issue when using the TRS balanced output:

View attachment 109301

This is quite a competent performance for such a budget, multifunction device:
View attachment 109302

Dynamic range was good:

View attachment 109303

As was jitter:

View attachment 109304

Unfortunately even though Chinese manufacturers have figured out how to get rid of the increase in intermodulation distortion when using ESS DAC chips, the news has not gotten to M2 yet:

View attachment 109305

Unlike pro interfaces with their own power supplies, there is not much more output to be had than the 4 volts I test:
View attachment 109306

I was pleasantly surprised to see a proper reconstruction filter that chops everything off at 22 kHz rather than the common 24 kHz:
View attachment 109307

Linearity was almost perfect:
View attachment 109308

Distortion rises with frequency but not enough to be a concern:
View attachment 109309

View attachment 109310

Motu M2 Measurements: ADC
For this testing, I used TRS input in the front:

View attachment 109311

Specification is confusing but seems to imply if you use TRS, you have lower gain and reference would be 16 dBu. That did not happen with my testing. Clipping occurred at a low 2.5 volts as opposed to minimum of 4 volts. You can see that in this sweep as well:

View attachment 109313

Notice also how distortion rises well before clipping.

Overall ranking is average and below Motu M4:
View attachment 109316


We also see rising distortion at both ends of frequency spectrum:
View attachment 109314

Fortunately our hearing thresholds are higher in those extremes so this is less of an audible problem than pure engineering.

Frequency response was wide enough at 192 kHz sampling:

View attachment 109315

Motu M2 Measurements: Headphone Amplifier
Power is usually an issue with these types of headphone outputs so let's jump right into that:
View attachment 109317


View attachment 109318

Not much power but what is there is good prior to clipping. So if you use a sensitive headphone, this may be a workable solution.

Conclusions
The DAC implementation in Motu M2 is quite good especially given the price. Clearly attention was put in to produce a good design. On ADC side, looks like they wanted to tier this down below the M4 and performance there is just adequate. Headphone amplifier is barely adequate from power point of view but otherwise, not bad.

Still, the package is well worth considering over a DAC-only solution. You get nice VU meters, mic and analog in ADC and passable headphone output for an extra $80. Good trade in my book.

Overall I am happy to recommend the Motu M2. If you can though, spend the other $60 and get the M4 as that has better ADC and two more channels.

------------
As always, questions, comments, recommendations, etc. are welcome.

Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

I very much wanted to love this sleek little unit; the build and functionality are just great. But I have to agree that M2 preamp-ADC audio quality is only so-so.

I did A/B needle-drop recording comps with (believe this or not) a Realtek ALC3271-CG CODEC in a Dell XPS 13 9305. The PC ADC recordings sound much clearer, more open, and less congested than the M2 recordings. This audible distortion I heard usually correlates with elevated IM. Unfortunately, I cannot find any measurements for the Realtek line input on the Dell to compare with the M2.

The source audio was unbalanced consumer line-level stereo. I fed the M2 via TRS inputs (tip and sleve only connected, ring floating). The PC line input was unbalanced.

I was so hoping the M2 would perform well sonically! It sounded much like the NAD PP4, which is not very good. Maybe Dell and Realtek have created a sleeper?

 

[AnalogSteph]

The Dell uses the somewhat notorious Waves MaxxAudio software, which may be messing with things if it hasn't been disposed of already. What sort of preamp did you use? The Dell only seems to have a mic input option, so I guess the customary 2.2 kOhm input impedance (which may cost you some low end should the phonopre have particularly small output coupling capacitors or generate extra distortion if its driving abilities are best described as wimpy), while the M2 TRS in doubles as a guitar input at 1 Megohm and everything should be able to drive it no problem.

 

[lkanies]

I have an M2 that I've been using for a year or so with no problems, but I recently started using it with a shotgun mic connected and now when I'm on a video call the person I'm talking to can't hear me if they're also talking.

I used a USB shotgun mic for a while, but other users found it too confusing to switch between that and the M2. So I bought an XLR shotgun mic, so everyone can just use the knobs on the M2.

However, when I use the XLR mic, it's kind of half duplex -- that is, we can always hear the other person talking, but if we both talk at once, they can't hear us. It seems like the M2 is cutting out the mc input if there's any output. I can still see the input on the line in monitor, but it's not making it to the apps somehow.

If I switch to another mic -- whether the USB shotgun mic or the crappy mic on my video camera -- then it works as expected: We can talk over each other and still hear each other.

Thus, I am assuming that the M2 is the problem.

To close the loop (foreshadowing there) on this, I figured out the problem:

For reasons I do not understand, my Mac Studio is using the Motu loopback interface by default. I know the Motu driver creates this loopback interface -- it's one of their advertised features -- but everything I've read says I can only select it in special apps like Logic Pro. Indeed, the only app I can find any evidence of it in is Audio MIDI Setup.

I figured it out playing video games with my kids -- all of my other testing had been in Zoom or Facebook, with talking. Once I started gaming, *all* of the audio got sent to them.

So, I tested it by recording myself in Zoom, and then muted the loopback interfaces in Audio MIDI Setup. Sure enough, the extra music went away. If this hadn't worked, I would have uninstalled the driver to test. It's pretty frustrating that the Mac does not provide this kind of fine-grained audio channel choices in the main settings like Windows does.

No idea why my mac is using the loopback by default or if I can change that. But at least I have a fix and can get rid of the extra mic on my desktop (and stop looking for a replacement for the M2).

 

[bequietjk]

What's up guys. Came to seek some advice on how to diagnose an issue with the M2. My unit has been cutting out (sound will not come through sporadically, then come back on when it wants to) over the past year and has recently just become pretty bad, very consistently. Unplugging the usb cable to pc helps sometimes, sometimes it doesnt. Turning the switch on the back on and off is a hit or miss as well. Wondering if anyone else has had this issue, and or what route I can take to fix it.

I appreciate any help

Worst comes to worst I'll just have to pickup another audio interface which I'm absolutely not opposed to seeing that I got a good 3 years of life out of this one.

 

[dshreter]

What's up guys. Came to seek some advice on how to diagnose an issue with the M2. My unit has been cutting out (sound will not come through sporadically, then come back on when it wants to) over the past year and has recently just become pretty bad, very consistently. Unplugging the usb cable to pc helps sometimes, sometimes it doesnt. Turning the switch on the back on and off is a hit or miss as well. Wondering if anyone else has had this issue, and or what route I can take to fix it.

I appreciate any help

Worst comes to worst I'll just have to pickup another audio interface which I'm absolutely not opposed to seeing that I got a good 3 years of life out of this one.

Have you tried it with a different PC? I had some USB reliability issues I seemingly couldn’t fix despite lots of troubleshooting, but it has been glitch free on another system.

 

[bequietjk]

Have you tried it with a different PC? I had some USB reliability issues I seemingly couldn’t fix despite lots of troubleshooting, but it has been glitch free on another system.

I may have to get behind my case and try all the ports there. No other PC to use so this may be the deciding factor.

 

[carat]

Has anyone attempted to connect an iPhone's 3.5mm output to one/both of the M2's TRS inputs? I know the ports are supposed to handle "line-level" signals, but I've seen complaints of poor results using the M2 with Line-level sources, and the iPhone isn't exactly line-level to begin with.

I want to capture FaceTime calls from the phone, using a 3.5mm TRS to 2x 6.35mm TS breakout adapter, running only one channel of this into the M2 and discarding the other (FaceTime is mono anyway), while simultaneously using the M2's other input for something else.

I know this is probably a niche case, but has anyone attempted it?

 

[AudioSceptic]

Has anyone attempted to connect an iPhone's 3.5mm output to one/both of the M2's TRS inputs? I know the ports are supposed to handle "line-level" signals, but I've seen complaints of poor results using the M2 with Line-level sources, and the iPhone isn't exactly line-level to begin with.

I want to capture FaceTime calls from the phone, using a 3.5mm TRS to 2x 6.35mm TS breakout adapter, running only one channel of this into the M2 and discarding the other (FaceTime is mono anyway), while simultaneously using the M2's other input for something else.

I know this is probably a niche case, but has anyone attempted it?

I don't see why that wouldn't work, although I think you'll have to turn the iPhone's volume pretty high.

 

[AnalogSteph]

Could anyone confirm the issue that is mentioned here (microphone input distorts when using headphones to monitor at the same time - I think he's got an older AKM-equipped version):

That would s-u-h-c-k. I entirely get how such a problem could be missed during development as every function is being tested in isolation (only), but it would definitely constitute a major flaw for a standard use case of such an interface.