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Motu M2 Review (Audio Interface)

amirm

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#1
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:

Motu M2 Review Audio Interface.jpg


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):

Motu M2 Review Audio MIDI Interface.jpg


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:
Motu M2 Measurements Audio Interface DAC Unbalanced.png


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

Motu M2 Measurements Audio Interface DAC balanced.png


This is quite a competent performance for such a budget, multifunction device:
best audio interface review 2021.png


Dynamic range was good:

Motu M2 Measurements Dynamic Range Audio Interface DAC.png


As was jitter:

Motu M2 Measurements Jitter Audio Interface DAC balanced.png


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:

Motu M2 Measurements IMD distortion Audio Interface DAC balanced.png


Unlike pro interfaces with their own power supplies, there is not much more output to be had than the 4 volts I test:
Motu M2 Measurements THD+N vs Level Audio Interface DAC balanced.png


I was pleasantly surprised to see a proper reconstruction filter that chops everything off at 22 kHz rather than the common 24 kHz:
Motu M2 Measurements DAC Filter Audio Interface DAC balanced.png


Linearity was almost perfect:
Motu M2 Measurements Linearity Audio Interface DAC balanced.png


Distortion rises with frequency but not enough to be a concern:
Motu M2 Measurements Multitone Audio Interface DAC balanced.png


Motu M2 Measurements distortion versus frequency Audio Interface DAC balanced.png


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

Motu M2 Measurements Audio Interface ADC balanced.png


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:

Motu M2 Measurements input level versus distortion Audio Interface ADC balanced.png


Notice also how distortion rises well before clipping.

Overall ranking is average and below Motu M4:
Best audio interface review.png



We also see rising distortion at both ends of frequency spectrum:
Motu M2 Measurements distortion versus frequency Audio Interface ADC balanced.png


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:

Motu M2 Measurements frequency response Audio Interface ADC balanced.png


Motu M2 Measurements: Headphone Amplifier
Power is usually an issue with these types of headphone outputs so let's jump right into that:
Motu M2 Measurements Audio Interface Headphone.png



Motu M2 Measurements Audio Interface Headphone power 32 ohm.png


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/
 

Ron Texas

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#4
Very nice, a balanced DAC with decent performance for $179 and they throw in an ADC for needle drops or whatever. I wonder if the warm up problem in the unbalanced output is something which will get worse and fail, or just go away. Thank you @amirm
 

Blumlein 88

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#6
Have you reviewed any pro audio gear that measures up to the audible range of high end DACS?
Lynx HiLo, Universal Apollo was in the running. RME too. MOTU 624 is just a bit (6 db pun intended) behind.
 

bigjacko

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#7
I must say it is crazy give how good the performance and how much money it costs. The filter is the cleanest one on ASR and plus all those functionality. Thanks Amir for measuring this and make me interested in Motu now. BTW is there an other measurements for headphone out like impedence?
 

617

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#8
I have the M4, which has a few more inputs/outputs and some extra monitoring features. I vastly prefer it to the multi box situation I had before, for controlling headphones and monitors at a computer. I have the monitor outs connected to powered monitors and keep my headphones plugged in. I control which one I listen to by using the separate volume controls.

This functionality, combined with the immense convenience of the additional inputs/outputs/beautiful meters/super low latency has sworn me off so called audiophile dacs/headphone amps. If you want to get audio into or out of a computer this is probably the best way to do it for most people.

Also I like that they design these things in my backyard in Harvard Square.
 

hardisj

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#9
Man, I just literally was typing up a For Sale post for one (I purchased two; details in the thread here if anyone is in the market). I went to link the M4 review and the search returned this thread. What a coincidence!


Yes, I have been using the M2 for my YouTube reviews, headphone listening and plan to use it to hook up some small monitors at some point. Such a lovely unit. Aside from the great specs, it's just a very well-built piece of equipment. Very robust feeling and - I know it is cheesy - I love the LCD meters. Makes level-matching my audio with people in my livestreams easy.
 

Χ Ξ Σ

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#10
So... Motu raised the price, I hope they also raised the bar for quality control. I bought six of these devices, all of them have some sort of cosmetic imperfections as you can see in the attached pictures. The first one I had also had pretty bad light leakage on the edge of the screen. I returned the first one immediately and did not take a picture. Not sure if this would bother the pro users though.

Other than that, stunning performance, nice feeling knobs, and how about those VU meters! For casual listeners like me who are fed up with paying a premium for a DAC's balanced output, this the best bang for the buck.
 

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lc155

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#11
So... Motu raised the price, I hope they also raised the bar for quality control. I bought six of these devices, all of them have some sort of cosmetic imperfections as you can see in the attached pictures. The first one I had also had pretty bad light leakage on the edge of the screen. I returned the first one immediately and did not take a picture. Not sure if this would bother the pro users though.

Other than that, stunning performance, nice feeling knobs, and how about those VU meters! For casual listeners like me who are fed up with paying a premium for a DAC's balanced output, this the best bang for the buck.
I have a feeling this is probably due to the pandemic and supply issues, along with demand outstripping supply. So they're probably pushing out subpar cosmetic QC that they'd normally catch out of necessity.
 

lc155

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#12
I have the M4, which has a few more inputs/outputs and some extra monitoring features. I vastly prefer it to the multi box situation I had before, for controlling headphones and monitors at a computer. I have the monitor outs connected to powered monitors and keep my headphones plugged in. I control which one I listen to by using the separate volume controls.

This functionality, combined with the immense convenience of the additional inputs/outputs/beautiful meters/super low latency has sworn me off so called audiophile dacs/headphone amps. If you want to get audio into or out of a computer this is probably the best way to do it for most people.

Also I like that they design these things in my backyard in Harvard Square.
Pretty much. The DAC is as good as it's gonna get in all practical aspects, and if you need more power for headphones (it is fairly current limited), you can just slap a cheap amp off the lineouts, and you're good to go.
 
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617

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#13
I have a feeling this is probably due to the pandemic and supply issues, along with demand outstripping supply. So they're probably pushing out subpar cosmetic QC that they'd normally catch out of necessity.
I got mine around when it came out and they were in short supply then. I suspect they've had trouble keeping up with demand due to how good these units are. Feature for feature much better than Focusrite or whatever.
 

Xyrium

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#14
These low end pro solutions are really kicking up the performance lately, very nice.

That said, it's unfortunate that folks are still not resolving the ESS hump. One would think it's in ESS' best interest, to share a few best practices in order to make their products shine. Still, a very nice overall result, IMO.
 
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amirm

amirm

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Thread Starter #16
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amirm

amirm

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Thread Starter #18
Which one is the second audio interface you have in line? I believe you said you had 2 waiting?
RME ADI-2 Pro V2.
 

Pearljam5000

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#20
So how much worst the M2 will perform vs the M4 purely as DAC+ volume control when connected to active studio monitors ?
 

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