Motu M6 killing sound stage & quality for headphones?

[caedin8]

So I recently got my first audio interface to do some recording, but in the mean time it has become a full time DAC on my desk setup.

My signal chain is now setup like this: PC -> Audio Interface -> outputs 1 & 2 TRS to XLR balanced outputs -> Topping A30 Pro XLR Inputs -> Hifiman HE6se

My first try was with the Scarlett 4i4 4th Gen, and it sounded absolutely wonderful. The sound stage is so good and clean, it's the best the Hifiman HE6se have sounded for me. (Maybe just with the extra headroom of have balanced inputs).

But, I needed to actually record 4 mic inputs, so I needed a more capable interface. There wasn't a 4th gen of the larger scarlett series yet, so I bought the MOTU M6. Plugging the MOTU M6 into the same signal chain above, but I was pretty disappointed to hear the sound quality is actually quite a bit worse. The volume is there, I can pump them to painful levels but it's like the clarity is gone, and the sound is muddier, boxier, less transparent.

I am not an expert at this so I am probably doing something wrong or misunderstanding some audio concept. Can anyone give me advice? I can't keep both, and I can't really go back to the audio quality pre-scarlett, but I also need the extra inputs, so I kind of stuck in a bind. If I can get MOTU working with the same quality I'd be really happy!

 

[Dunring]

Are you just powering it with USB, or do you have the 1 amp power supply on it as well?

 

[kemmler3D]

So I recently got my first audio interface to do some recording, but in the mean time it has become a full time DAC on my desk setup.

My signal chain is now setup like this: PC -> Audio Interface -> outputs 1 & 2 TRS to XLR balanced outputs -> Topping A30 Pro XLR Inputs -> Hifiman HE6se

My first try was with the Scarlett 4i4 4th Gen, and it sounded absolutely wonderful. The sound stage is so good and clean, it's the best the Hifiman HE6se have sounded for me. (Maybe just with the extra headroom of have balanced inputs).

But, I needed to actually record 4 mic inputs, so I needed a more capable interface. There wasn't a 4th gen of the larger scarlett series yet, so I bought the MOTU M6. Plugging the MOTU M6 into the same signal chain above, but I was pretty disappointed to hear the sound quality is actually quite a bit worse. The volume is there, I can pump them to painful levels but it's like the clarity is gone, and the sound is muddier, boxier, less transparent.

I am not an expert at this so I am probably doing something wrong or misunderstanding some audio concept. Can anyone give me advice? I can't keep both, and I can't really go back to the audio quality pre-scarlett, but I also need the extra inputs, so I kind of stuck in a bind. If I can get MOTU working with the same quality I'd be really happy!

This is not a highly scientific comment because I am not referencing the impedances or power rating of the M6, but I did find that my M2 would sometimes struggle to provide phantom power over USB. When I turn on phantom power sometimes it will start glitching out. Which tells me maybe it was underpowered over bus power on the port I had it connected to. Extrapolating that further, maybe these interfaces can end up underpowered over USB, which could maybe lead to clipping and impaired sound quality.

Anyway, a lot of ifs, but if you are running it on USB try using a dedicated PSU instead and see if you hear anything changing in a night-and-day way.

 

[caedin8]

Are you just powering it with USB, or do you have the 1 amp power supply on it as well?

Initially I thought it might be under-powered as well, so I plugged in the power supply pretty early on in my A/B testing between the two interfaces. Unfortunately that wasn't it.

 

[kemmler3D]

Dumb question but are you 100% sure the headphones are plugged in all the way?

 

[caedin8]

Dumb question but are you 100% sure the headphones are plugged in all the way?

Yeah, I went back and forth dozens of times. Mostly switching the output cables between the interfaces, and I swapped and tried another headphone as well at one point

 

[OK1]

Is it possible that the MOTU is more transparent - telling you the truth. Based on reviews of the earlier models, and one may assume the same (a dangerous thing assuming, cos these manufacturers have the right to change specs - especially when they have not included the spec in their published specs - so you cannot hold them to something they have NOT said), output impedance of the headphones jacks, which was low - according to the tests by Julian Krausse on Youtube.

I am aware that the impedance of the 4th gen 4i4 is higher than desirable, for low impedance headphones - see link below, for comparison.

Focusrite Scarlett 4th Gen

I hadn't noticed that the headphone outputs are actually different between the 4th gen 2i2 and 4i4... huh. That's one way to upsell you on the more expensive model, I guess.

audiosciencereview.com

WIth the exception of SSL and Toppings audio interfaces and I think Rode, headphone interfaces on the budget end, are in my opinion, added to sweeten the deal. By and large I think, over time most of us should migrate to using a good high quality external headphone amp, which we can pair to any audio interface. The cost of these desktop headphone amps, is coming down. To the point where $100 or less like the Modi Heretic(looks like its now less than $70 excluding sales tax) , gets you the kind of audio quality you'll get from the headphone outputs in high end audio interfaces, without spending exorbitant sums. Headphone amps are probably the weakest link in these products.

Edit: Please ignore all of the above. The issue has nothing to do with the headphone amp of the Motu Audio interface. Cos a pretty decent headphone amp, the Topping productk is already in use, as per my suggestion above.

 

[Joachim Herbert]

My signal chain is now setup like this: PC -> Audio Interface -> outputs 1 & 2 TRS to XLR balanced outputs -> Topping A30 Pro XLR Inputs -> Hifiman HE6se

Did you take the Topping A30 out of the chain to make that PC -> Audio Interface -> Hifiman HE6se? Sounds like you did.

 

[TheLastGerman]

As you can read at the beginning, there is a not bad headphone amplifier in the chain, so the problem is not the amplification for the headphones. I don't mean to imply that it can be generalized with respect to the brand, but I had similar experiences with a Motu 8a that I used as an active crossover. No matter what I tried, the sound was somehow flat, two-dimensional and dead. Loopback tests showed no abnormalities whatsoever. Even in two-channel mode with passive loudspeakers, the difference in spatiality compared to an RME ADI-2 DAC was clearly perceptible. Only the change to a Topping DM7 brought the desired sound experience.

 

[OK1]

As you can read at the beginning, there is a not bad headphone amplifier in the chain, so the problem is not the amplification for the headphones. I don't mean to imply that it can be generalized with respect to the brand, but I had similar experiences with a Motu 8a that I used as an active crossover. No matter what I tried, the sound was somehow flat, two-dimensional and dead. Loopback tests showed no abnormalities whatsoever. Even in two-channel mode with passive loudspeakers, the difference in spatiality compared to an RME ADI-2 DAC was clearly perceptible. Only the change to a Topping DM7 brought the desired sound experience.

I see - he is using a pretty good headphone amp - the Topping. Thanks for drawing my attention to this. Appreciated.

 

[OK1]

OK lets drill down into this, and trace the audio path, now I am clear that its the analog line outputs of the audio interface that are in the path.

FOCUSRITE

Below are the manufacturer specs of the Focusrite 4i4 4th generation, from this page :

Scarlett 4i4

Focusrite Scarlett 4i4 is the complete compact studio hub for all your instruments, perfect for multi-instrumentalists and collaborators.

focusrite.com

MOTU

Below are the manufacturers specs, from this page

Specs | MOTU.com

motu.com

These are highly reputable equipment producers, and their specs can be relied on, with the only accomodation being that NOT every single device of this model, will measure the same

Both audio interface outputs are specced similarly, but we do not know the output impedance of the MOTU, unfortunately.

Could it be the volume in Windows is set different for each device?, if playback is NOT using WASAPI exclusive or ASIO? It's so easy to have this anomaly. Suggest ensuring that WASAPI exclusive or ASIO is the route out of the app in Windows

 

[Joachim Herbert]

I'd rather wait for @caedin8 to answer my question . Unless there is something seriously broken there should be no audible difference between the two interfaces acting as a DAC. Both are as transparent as it can get.

 

[caedin8]

Did you take the Topping A30 out of the chain to make that PC -> Audio Interface -> Hifiman HE6se? Sounds like you did.

I did try this, but it’s hard to validate because the headphone amplifier in the audio interface for both the Scarlett and Motu are underpowered for the Higiman HE6se, so it was a bit inconclusive.

I tried with some Hifiman HE 560 v4 which are easier to drive, and I didn’t really notice a difference between the Scarlett and Motu with those phones and not using the Topping, but the quality wasn’t as high, which is to be expected from the cheaper phones. So this did help me some, but added a lot of variables so I wasn’t able to find anything conclusive.

For what it’s worth I thought the Hifiman HE560 v4 directly in the Motu sounded pretty good. Let me try that again this morning with EQ and see what I think.

I read somewhere last night that the Motu interface output is 3.6v and the Scarlett is 5v which might have a difference, but I couldn’t find anything about it in the spec sheets, but a random Reddit comment. Not sure if that’s a red herring or not. The other thing I started looking into is impedance mismatch, as one of the symptoms I read online (loss of treble) could attribute to lack of sound stage and loss of detail, so it might be what I’m experiencing. But I’m new to all of this so not really sure how to validate it’s an impedance issue.

 

[caedin8]

OK lets drill down into this, and trace the audio path, now I am clear that its the analog line outputs of the audio interface that are in the path.

FOCUSRITE

Below are the manufacturer specs of the Focusrite 4i4 4th generation, from this page :

Scarlett 4i4

Focusrite Scarlett 4i4 is the complete compact studio hub for all your instruments, perfect for multi-instrumentalists and collaborators.

focusrite.com

View attachment 373105

MOTU

Below are the manufacturers specs, from this page

Specs | MOTU.com

motu.com

View attachment 373107

These are highly reputable equipment producers, and their specs can be relied on, with the only accomodation being that NOT every single device of this model, will measure the same

Both audio interface outputs are specced similarly, but we do not know the output impedance of the MOTU, unfortunately.

Could it be the volume in Windows is set different for each device?, if playback is NOT using WASAPI exclusive or ASIO? It's so easy to have this anomaly. Suggest ensuring that WASAPI exclusive or ASIO is the route out of the app in Windows

I’ll check this today. I’ve installed both the motu drivers and Scarlett drivers, and can select between the focusrite or motu in windows. In Ableton device settings the focusrite is clearly listed as focuseite usb ASIO while the Motu simply says Motu M6.

Volume for both is 100 out of windows in testing. I’m not really sure how to force the motu device to use ASIO or in other words use ASIO with Motu, it’s a little foreign to me.

 

[Joachim Herbert]

I read somewhere last night that the Motu interface output is 3.6v and the Scarlett is 5v which might have a difference...

Seems you did not level match (within less than .5 dB or preferable .2 dB), which you have to do for any valid comparison. The louder otherwise always wins in all aspects you can imagine.

 

[caedin8]

Seems you did not level match (within less than .5 dB or preferable .2 dB), which you have to do for any valid comparison. The louder otherwise always wins in all aspects you can imagine.

Sorry I did level match by ear as best I could, so the output dial on the Motu is around the 4 o clock position so that when switching between the Scarlett and the Motu I don’t have to adjust the dial on the headphone amplifier, they should be right about the same sound level.

For the Scarlett the output dial is at max, and the sound level is set to -12 dbfs in Scarlett control 2 software. For Motu there is no bundled software mixer so I’m just using the physical output dial to 4pm.

 

[OK1]

I'd rather wait for @caedin8 to answer my question . Unless there is something seriously broken there should be no audible difference between the two interfaces acting as a DAC. Both are as transparent as it can get.

I thought it important to compare the max output levels on the line-outs, cos if it varied significantly and it sometimes does, e.g if you have a look at the Behringer products, their max output level, which corresponds to 0 dBFS, is lower than these two, and in that case may explain the difference. But in this case' it's identical, so we can rule out any variance from this.

 

[Joachim Herbert]

You really need to do proper level matching. As pointed out even minor differences determine your preference.

You may want to try to listen to any of your interfaces at the minimum level you feel comfortable with and then turn up the volume a bit. You will find a richer, fuller more spatious sound. Maybe even a darker background and blacker blacks.

Also, if you lower the volume of your preferred interface you will loose a lot of the qualities you love.

I learned about this when I traded a Mark Levinson No. 360s DAC for an Apogee Pro DAC. The Apogee just blew my mind. Hoping to get a further upgrade I gave the Apogee away for a Cello branded consumer version, which was sort of underwhelming. Turned out the difference was due to pro vs. consumer level output and how I handled it (I did not, really).

 

[OK1]

Sorry I did level match by ear as best I could, so the output dial on the Motu is around the 4 o clock position so that when switching between the Scarlett and the Motu I don’t have to adjust the dial on the headphone amplifier, they should be right about the same sound level.

For the Scarlett the output dial is at max, and the sound level is set to -12 dbfs in Scarlett control 2 software. For Motu there is no bundled software mixer so I’m just using the physical output dial to 4pm.

Some thoughts. As both audio interfaces are specced to the same maximum output of +16dbU, if this is true, that means at 0dBFS (zero decibels full scale), both of them will generate the same output.

Therefore the Windows settings (volume level in Windows), if set to the same thing, will produce the same output.

Here is what I suggest.

1. Set the Windows volume to max. Set the Scarlett output dial to max, and sound level in Scarlet control panel to 0 dBFS.

Use the headphone volume control to set the level that you think is suitable for your listening.

2. When you change over to the Motu interface, Set the Windows volume of the MOTU interface to max, set the physical volume control of the Motu line outs, to max, do not change the headphone volume control, from what you had set it to, when using the Scarlett.

Unless there is something else changing the volume, we should expect that the loudness from playback through either of the audio interfaces, should now be the same. I hope.

 

[Joachim Herbert]

Some thoughts. As both audio interfaces are specced to the same maximum output of +16dbU, if this is true, that means at 0dBFS (zero decibels full scale), both of them will generate the same output.

This would be a rare case of delivering on the specs. As even small deviations change perception, you need to calibrate (measure and adjust).