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MOTU M6 Audio Interface Review

Rate this audio interface:

  • 1. Poor (headless panther)

    Votes: 5 3.5%
  • 2. Not terrible (postman panther)

    Votes: 47 33.3%
  • 3. Fine (happy panther)

    Votes: 82 58.2%
  • 4. Great (golfing panther)

    Votes: 7 5.0%

  • Total voters
    141
The Trim control was barely above its minimum. Same issue exists with setting the trim to minimum and increasing input level to what the spec calls for.

What spec are you referring to?

The combo jack line input has a specified max input level of +16 dBu (4.9 V). It doesn’t take much gain to hit that when starting from +14.3 dBu (4 V).

In your review you seem to claim the specified max input level for the combo jack line in is +18 dBu but this isn’t the case, only line inputs 5/6 have a specified max input of +18 dBu.

Michael
 
In your review you seem to claim the specified max input level for the combo jack line in is +18 dBu but this isn’t the case, only line inputs 5/6 have a specified max input of +18 dBu.
That input saturates at +18 dBu:

index.php
 
That input saturates at +18 dBu:

index.php

That is clear from your review.

What isn’t clear is how much preamp gain (if any) was applied for the dashboard and THD+N vs level measurements of inputs 1/2. I would have assumed gain was at minimum (+0 dB) but this isn’t clear from your comments about increasing gain and then backing it off.

If the THD+N vs level sweep has 0 gain applied and 0 dbFS is +18 dBu, it seems like quite a big miss that the best THD+N occurs as +8 dBu (-10 dBFS) when MOTU specs best performance of the combo jack line in at +14 dBU.

Michael
 
Specs from manual gives separate figures for XLR (Mic - XLR/TRS combo when using XLR), TRS (XLR/TRS combo when using TRS) or Line inputs.
 

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Specs from manual gives separate figures for XLR (Mic - XLR/TRS combo when using XLR), TRS (XLR/TRS combo when using TRS) or Line inputs.
The 70Hz - 20kHz spec sticks out more. Haven't seen an input cutting so early anywhere else.
 
Specs from manual gives separate figures for XLR (Mic - XLR/TRS combo when using XLR), TRS (XLR/TRS combo when using TRS) or Line inputs.
That was mentioned in the review and was considered in the testing.
 
What isn’t clear is how much preamp gain (if any) was applied for the dashboard and THD+N vs level measurements of inputs 1/2.
There is no indication of that as an analog value. You are going form analog to digital samples. All I can tell you is where I set the trim.
 
Thanks Amir. I always look forwards to audio interface tests. I'm thinking about getting the 16A (2025) for use as 16ch home theater DAC. Sounds encouraging.
Curious, what kind of setup were you thinking of? Like connection strategy?
 
The 70Hz - 20kHz spec sticks out more. Haven't seen an input cutting so early anywhere else.
Thats a weird spec. It says -.15db not the standard -3db at 70hz but Amirms measurement shows its flat to 10hz.
 
Thats a weird spec. It says -.15db not the standard -3db at 70hz but Amirms measurement shows its flat to 10hz.
That's for the TRS / TS combo input. Amir measured the FR of the output via USB, not the FR of any input.

I have an M4. I might sweep that input and see what it does. I have not noticed any high pass using electric guitar or electric bass. The low E on guitar is 82Hz, and the Low E on a 4 string bass is 41Hz. That would be a very strange design choice if true.
 
That's for the TRS / TS combo input. Amir measured the FR of the output via USB, not the FR of any input.

I have an M5. I might sweep that input and see what it does. I have not noticed any high pass using electric guitar or electric bass. The low E on guitar is 82Hz, and the Low E on a 4 string bass is 41Hz. That would be a very strange design choice if true.
A typo probably. And a weird one.
 
Disappointed to see this is a 6 x 4 unit, so only 4 channels of output. If it were 6, it could be used with a PC and a computer player like JRiver as a 5.1 home theater control center, which would be great given its modest price and the high level performance of its DACs.

As alway, great review Amir.
 
Curious, what kind of setup were you thinking of? Like connection strategy?
This is what I think a system needs to do:
  • Media playback
  • Source selection
  • Audio codec decoding
  • Immersive audio decoding
  • Amplitude equalisation
  • Phase equalisation
  • D to A conversion
  • Pre-amplification
  • Volume Control
  • Power amplification
This is how I plan to build the system, using Audiolense + convolver (PC DSP) to perform frequency and phase correction:

Player > HDMI > Nuprime H16A > Dante > PC DSP > USB > MOTU 16A > Analogue > Power Amps

These are the benefits of doing it this way:
  • High processing power
  • Relatively low cost
  • Compact and quiet
  • Easy upgrading route
  • Open, flexible, scalable, non-proprietary architecture
  • Physical separation of processing & conversion & amplification
  • Opportunity to use any DSP digital audio output
  • Opportunity to use any unit for each function
  • Opportunity to use active loudspeakers
  • Opportunity to perform speaker cross-overs in DSP
 
This is how I plan to build the system, using Audiolense + convolver (PC DSP) to perform frequency and phase correction:
Interesting. You're using a decidedly different definition of proprietary, of which I've previously been unaware. I'd argue it's still quite proprietary (Izotope products are as proprietary as they come), though it is modular, but there's no point in quibbling.

The ability to pass the audio through DAW plugins like AudioLens or Ozone, for example, is quite interesting.
 
Disappointed to see this is a 6 x 4 unit, so only 4 channels of output. If it were 6, it could be used with a PC and a computer player like JRiver as a 5.1 home theater control center, which would be great given its modest price and the high level performance of its DACs.

As alway, great review Amir.
It depends on what you classify as an "output"; usually MIDI, USB, and headphones are considered outputs for audio interfaces at this level.

Marketing types like to count every possible connector, regardless of whether they are discrete audio channels.
 
Unacceptable performance for a $400 audio interface...fair if you don't buy it for its main purpose. Back to the hunt for something with more than 4 io and/or ADAT
 
Interesting. You're using a decidedly different definition of proprietary, of which I've previously been unaware. I'd argue it's still quite proprietary (Izotope products are as proprietary as they come), though it is modular, but there's no point in quibbling.

I don't think proprietary is the important word. My intention was to highlight the importance of the architecture over the products, and that it didn't use an expensive, ready-made, end-to-end solution, like Trinnov, Genelec, Merging, Neumann, StormAudio or Avid.

Yes, it's a modular or layered solution, and each layer can be substituted or upgraded without affecting the function of the architecture. I put the Nuprime H16A in as the decoder, and the Motu 16A as the converter, as they broadly meet the requirements for that layer, but they could be substituted by an Arvus H2-4D or an Antelope Orion Studio or two Okto DAC8.

The system isn't constrained to the number of channels - you could start off with 8, and extend to 12 or 16 later on. You could easily go to 32 if you wanted the DSP PC to handle speaker cross-overs. If audio interfaces continue to improve in performance, there's an easy upgrade path. If Antelope, AVID, DAD, Merging, Lynx etc start to use more sophisticated room correction than simple PEQ (Dirac is the obvious possibility, though I believe Sonarworks have something in the pipeline) then the architecture will accommodate that.

I think one of the key benefits is that each function is broken down to one layer, or one unit, and each one is as efficient and effective as possible. I put the MOTU 16A there as it seems to share technology with the M6 and has an uncommon combination of high performance and low cost.

I don't understand the reference to Izotope.

EDIT: I was referring to Juice HiFi Audiolense, which is a SW room correction tool, and not Izotope Audiolens.
 
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+10 dBu is exactly what the specs say.

not sure what happend with the inputs 5+6 though.

again, you don't aply gain to a line signal. that is simply not something you would do in real life.
 
again, you don't aply gain to a line signal. that is simply not something you would do in real life.
Once more you are not understanding the nature of testing. My intent is to level the playing field to get all devices, if possible, to capture at their full dynamic range. And this is near 0 dBFS with 4 volt input. If the only way to get there is by using the trim, I will do that.

As I said, I personally do that with my interface, setting my compressor to maximize the dynamic range by getting close but not exceeding 0 dBFS.

By your logic, the trim control should not be there.
 
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