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MOTU M4 interest?

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I wanted to simplify my desktop setup of a good head amp, a good dac, and an okay audio interface into one unit, so I got a new MOTU M4. This seems to be the best of the current cheap 4 in/4 out interfaces, similar to products from Behringer, Presonus, Steinberg, and Focusrite. Amir tested another MOTU interface in their mid tier price bracket and it did quite well (SINAD ~110db) so I thought I'd get their newer unit.

Features which set it apart:
Loopback recording
On/off switch
USB-C bus powered
Nice color LED screen with meters for each 4 inputs
Ability to direct monitor all 4 inputs
Individual switches for phantom power on mic inputs
Midi in/out
Apparently very low latency for a USB interface

I was enticed also by the advertised sound quality, described as having THD+N in the -110db range for the phone out and line out. -129dBu EIN for the mic inputs. This spec is 9db better than my Tascam battery powered portable interface which is pretty damn quiet.

ESS Sabre32 Ultra™ DAC technology for superb analog sound
☑ The same converter technology used in audio interfaces costing thousands
☑ Measured 120 dB dynamic range on outputs
☑ Measured -129 dBu EIN on mic inputs
☑ ESS-driven headphone output


Does anyone have any experience with this unit?
 

Severian

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I've had it for a couple of weeks and am very happy with it as an all-in-one solution. The headphone amp can power a pair of Sennheiser HD6XX at about 75% volume for typical rock music and sounds clean in the process. I like having the option to use the 3/4 outputs to run an external headphone amp. Anecdotally, I think my speakers sound a bit better from the unbalanced 1/2 monitor outputs than they did from my Atom/Modi 3 combo. I suspect this is probably because the volume control appears to be passive, whereas on the Atom the preamp outputs are connected to the headphone amp and could potentially have been clipping my DSP input. Just a theory.

Build quality is exceptional for the price. The knobs are excellent.

I haven't used any of the ADC functionality yet but I will soon.

The only feature I'm missing is is that I wish the headphone output could be assigned a different mix from the monitor output.
 

Minigun

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I wrote a somewhat extensive review about the M4 (link to review, my personal blog) from a Linux user perspective, in case someone else is interested. I listed some specs and info which I didn't find anywhere else and did some measurements (for example, THD+N -103 dB loopback) and checked realistic round-trip latency in Linux (6.5 ms @ 96000 Hz). I'm happy to report the device seems to work very nicely as a class-compliant device.

The build quality is very good, everything feels nice, especially the knobs. I've recorded some albums in the past, so I'll be also using the microphone inputs at some point. Based on quick testing and other reviews online, they are extremely good as well.

Headphone output was interesting how it behaved with different phones. I got huge bass with my earphones (KZ ZST) but not that much with my headphones (AKG K701). My previous mic/headphone amp wasn't that different with the two.
 

boXem

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I wrote a somewhat extensive review about the M4 (link to review, my personal blog) from a Linux user perspective, in case someone else is interested. I listed some specs and info which I didn't find anywhere else and did some measurements (for example, THD+N -103 dB loopback) and checked realistic round-trip latency in Linux (6.5 ms @ 96000 Hz). I'm happy to report the device seems to work very nicely as a class-compliant device.

The build quality is very good, everything feels nice, especially the knobs. I've recorded some albums in the past, so I'll be also using the microphone inputs at some point. Based on quick testing and other reviews online, they are extremely good as well.

Headphone output was interesting how it behaved with different phones. I got huge bass with my earphones (KZ ZST) but not that much with my headphones (AKG K701). My previous mic/headphone amp wasn't that different with the two.
Interesting that you managed to get the M4 running under Linux. I was under the impression that a kernel change was needed. Seems internet was wrong...
If you want, you can post your measurements here: https://www.audiosciencereview.com/forum/index.php?threads/motu-m4-loopback-measurements.10890/
 

jfetter

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M4 , Visual Analyzer and a spanking New icore3 laptop are my bench standard. Very hispeed setup.
Using my older W10 laptop for everything else.
 
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Thorskin

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Would something like this or a Scarlett Solo/2i2 or a umc404hd be an acceptable alternative to a Atom+D10 / Magni/Heresy+Modi?
I am shopping for a new DAC+AMP but also need a Audio interface so hoping something like this can take care of all 3.
Ill be using HD650s, LCD2cs and various iems.
 
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jfetter

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I'm now using the M4 as primary music dac, headphone amp and audio analyzer for circuit development.
Don't forget to allow RING to float on 1/4" rear panel jacks if going unbalanced.
Short 10" USB-C to USB-C with no adapters.
W10 is locked down no updates. (Static platform)
 

jae

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I'm now using the M4 as primary music dac, headphone amp and audio analyzer for circuit development.
Don't forget to allow RING to float on 1/4" rear panel jacks if going unbalanced.
Short 10" USB-C to USB-C with no adapters.
W10 is locked down no updates. (Static platform)

How do you find the amplifier? I'm in the process of getting a new AMP/DAC and headphone setup but I am undecided on what I'm getting as of now. Coincidentally I also need a new audio interface for microphone recording so I was wondering if this would be good enough to tide me over using it as an all-in-one amp/dac/interface with a wide variety of headphones (mostly HD650 and Audeze) until I got a separate AMP/DAC.
 

jfetter

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How do you find the amplifier? I'm in the process of getting a new AMP/DAC and headphone setup but I am undecided on what I'm getting as of now. Coincidentally I also need a new audio interface for microphone recording so I was wondering if this would be good enough to tide me over using it as an all-in-one amp/dac/interface with a wide variety of headphones (mostly HD650 and Audeze) until I got a separate AMP/DAC.

It excellent, but I've only used 32 ohm Grados. I would not think the HD650 will live up to its full potential with the TI-1688 headphone amp.
All M4 published specs are real.
 

jae

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Hmm, maybe with the balance output they would fair better
 

lc155

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I've had it for a couple of weeks and am very happy with it as an all-in-one solution. The headphone amp can power a pair of Sennheiser HD6XX at about 75% volume for typical rock music and sounds clean in the process. I like having the option to use the 3/4 outputs to run an external headphone amp. Anecdotally, I think my speakers sound a bit better from the unbalanced 1/2 monitor outputs than they did from my Atom/Modi 3 combo. I suspect this is probably because the volume control appears to be passive, whereas on the Atom the preamp outputs are connected to the headphone amp and could potentially have been clipping my DSP input. Just a theory.

Build quality is exceptional for the price. The knobs are excellent.

I haven't used any of the ADC functionality yet but I will soon.

The only feature I'm missing is is that I wish the headphone output could be assigned a different mix from the monitor output.

Gotta ask - does the bus power provide enough juice to this interface to allow for powering of high impedance headphones at the same time as using the mic input, particularly with +48v?

I have heard that with some interfaces, they may run into power restrictions while trying to do much all at once and I'm hoping this isn't the case here as I too would like to replace a dedicated o2dac setup with an all in one box if possible.
 

jfetter

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USB-C power. My previous interfaces were ur22 and ur22-ii USB2.
M4 includes a usb2 to usbc but kinda long so I did purchase some ultra short usbc to usbc in case its power hungry.
I measured the dcdc -+ rails but did not keep notes. Have not used the 47v.
The optical meters are useful too.
The headphone out can drive difficult line loads like loz passive filters too.
It just works all the time so really nice.
The driver works like a charm too. All my old problematic software works on m4 too.
 

lc155

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It's USB-C power, but using USB 2.0 protocols, so I doubt it is drawing the additional power that USB-C can do, unless I'm wrong and it is. I'll have to ask MOTU about that, actually.
 

Blumlein 88

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Gotta ask - does the bus power provide enough juice to this interface to allow for powering of high impedance headphones at the same time as using the mic input, particularly with +48v?

I have heard that with some interfaces, they may run into power restrictions while trying to do much all at once and I'm hoping this isn't the case here as I too would like to replace a dedicated o2dac setup with an all in one box if possible.
Phantom power is not supposed to need more than 10 ma per microphone input. Most microphones use less, some one tenth that. As that would be 480 milli-watts per microphone worst case it might be a bit of a strain. USB 2.0 can supply at least 2500 milli-watts. Some versions of it can supply 10,000 milli-watts.

I had one interface that was USB powered, but if you wanted phantom power you add to plug in an outboard supply.

There have been USB powered interfaces that can have the issues you bring up, though it isn't all that common. I don't happen to know in the case of the MOTU M4. The M4 manual does discuss that if using an iOS adapter for type C, an iPad will not power everything and phantom power. So the adapter suggested is a powered adapter and should be plugged into the wall. Apparently for most devices regular USB supplies will be sufficient.
 

jae

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J7Dmu16.png


Apparently the M4 measures better too. Clearly the best options at the price point until the RME stuff
 

lc155

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Severian

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Gotta ask - does the bus power provide enough juice to this interface to allow for powering of high impedance headphones at the same time as using the mic input, particularly with +48v?

I have heard that with some interfaces, they may run into power restrictions while trying to do much all at once and I'm hoping this isn't the case here as I too would like to replace a dedicated o2dac setup with an all in one box if possible.

I don't use the mic inputs so can't comment on that.

I will say that now the initial glow has worn off, I don't really consider the headphone output satisfactory for the 6XX. It does comfortably get up to listening volumes, but the bass and midbass in anemic. They sound much better driven by my Atom off the 3/4 line outputs. I haven't really done careful A/B testing of that though, so don't put too much stock in it. I also find it convenient to be able to use a separate EQ profile on the 3/4 outputs without needing to switch it off to avoid affecting my speakers.

My AKG K371s, on the other hand, sound great from the headphone out and I've seen no reason to drive them with the Atom. I also don't use EQ with them thanks to the Harman bass shelf, so it's a good pairing.
 

lc155

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I don't use the mic inputs so can't comment on that.

I will say that now the initial glow has worn off, I don't really consider the headphone output satisfactory for the 6XX. It does comfortably get up to listening volumes, but the bass and midbass in anemic. They sound much better driven by my Atom off the 3/4 line outputs. I haven't really done careful A/B testing of that though, so don't put too much stock in it. I also find it convenient to be able to use a separate EQ profile on the 3/4 outputs without needing to switch it off to avoid affecting my speakers.

My AKG K371s, on the other hand, sound great from the headphone out and I've seen no reason to drive them with the Atom. I also don't use EQ with them thanks to the Harman bass shelf, so it's a good pairing.

Surprising, given the incredibly low output impedance of the headphone output on the M2 (Less than 0.05ohms). We also know the distortion and noise from measurements places the M2 in a very good spot as well. I know the 650s can peak at 530ohms in the bass regions, but my technical knowledge isn't great enough on this subject to say if the M2 would struggle to deliver enough power in that region, but if it is getting loud enough, it should. The distortion figures to me seem unlikely that it would be clipping (which is what you'd probably be hearing if bass and midbass sounded anemic).
 
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