Best Audio Interface for Sennheiser HD 600 650 6XX for Music Production, Mixing, and Mastering - Replace MOTU M4?

[designfx]

Hi guys -- I've really enjoyed lurking and learning in this forum, great stuff, but this time I'm stumped, so I need some help/feedback. Here's my first post...

I do music production, mixing, and light mastering, and I have been using Sennheiser HD 600 650 6XX headphones with a MOTU M4 for my portable rig. I use an RME Fireface UFX III as my main studio interface.

I bought the MOTU M4 in part because of recommendations from this forum for portable use, but I'm just not loving the headphone out of the M4. I feel like it is not giving me what I need for the Sennheisers. It's not clear enough to me... and I've cross-checked this with another M4 on another system to confirm it's not my unit. Don't get me wrong... the MOTU M4 is not BAD. It's just not.... great. I feel like it's missing something and I get more out of the RME.

However, maybe the M4 is about the best I can expect in this price range? Or maybe it's just confirmation bias when I plug into the RME? I don't know, and I'm a bit frustrated. But I feel like I can do better than the MOTU M4's headphone outs. It's otherwise a great little unit.

So I was hoping you guys could suggest an alternative that is portable and affordable... I don't like taking too expensive of equipment with me with my laptop, so I'd like to keep it under $500-600 or so... Otherwise I would have already bought the RME Babyface Pro FS for $1000.

So my needs are:

• Preferably under $600
• Portable-ish - doesn't have to be tiny
• Best, most accurate headphone amp I can get for Sennheiser HD 600 650 6XX in this range
• Minimum 2-in/2-out with decent preamps for location recording. More i/o would be nice, but not strictly necessary
• Great ASIO drivers that are very stable and reasonably low-latency
• I don't mind carrying around an external power brick if that makes a big difference in headphone amp quality

I've been looking at all the forum threads, Julian Krauss videos, etc... and it seems like the recent Audient (iD14mkii, iD24) and SSL (SSL 2 plus mkii) devices are possibilities... but are they going to be better for the Sennheisers than the MOTU M4?

I'm even open to the Zoom UAC-232 or Apogee Boom, as simple as they are, if it improves headphone outs. These are all super affordable, again, I'm fine with up to about $600.

Or do I just focus on something larger with external power to properly drive the headphones?

Maybe spend a little more on the Audient iD44 mkii (~$700)?

Or will the MOTU UltraLite-mk5 (~$700) give me better performance than the M4? (Julian's numbers don't give me confidence though.)

Or has anyone tested to see if the Black Lion Audio Revolution 6X6 (~$550) fixed the shortcomings of the Revolution 2X2? I do like BLA in general, but it looks like the Revolution 2X2 had too many issues... maybe the 6X6 is what the 2X2 should have been?

Or do I just spend the $1000 on the Babyface Pro FS?

Any thoughts would be appreciated!

Thank you all for your great feedback in so many other threads!

 

[DVDdoug]

MOTU M4 is not BAD. It's just not.... great. I feel like it's missing something and I get more out of the RME.

If it goes loud enough (without clipping/distortion) it's probably fine... There should be no (audible) defects and no REAL difference.

Usually the most important thing with an audio interface is the quality of the mic preamps. You want low noise (and sometimes high gain, especially if you are using dynamic mics). And of course, sometimes the number if inputs is important!

Pros generally recommend against mixing & mastering with headphones. But I read something from an engineer that moves from studio-to-studio and he uses his headphones for consistency. He says your choice of headphones is not important once you've had time to learn what a good mix sounds like on them.

You don't need low latency for mixing & mastering. There is often hours, days, or weeks of "latency" from the time it was recorded and a few ore milliseconds don't matter. If you are monitoring yourself while recording then a noticeable delay can make it hard to perform. IMO it's best to use an interface with zero-latency direct-hardware monitoring, or maybe a USB mixer so the monitoring path doesn't go through the computer.

 

[designfx]

Thank you DVDdoug!

If it goes loud enough (without clipping/distortion) it's probably fine... There should be no (audible) defects and no REAL difference.

Indeed it could all be in my mind!

Usually the most important thing with an audio interface is the quality of the mic preamps.

In this case, preamps not too important to me, secondary to other priorities mentioned. But yes, I'd agree that usually it is important for most users!

Pros generally recommend against mixing & mastering with headphones.

I am a "pro" (in the sense that I make money from clients doing pro audio, whether or not it's worth what they pay me is something else entirely, lol!), but when I'm working outside the studio with my portable rig, I use HD 600/650 headphones and they fill in adequately. My brain is tuned to them now, most of my colleagues use them too. Many producers/engineers do something similar. But yes, there are some famous engineers that are fine even with the famous Sony MDR-7506 headphones and I always take a pair of those with me to cross reference mixes too. But I greatly prefer to stick with HD 600/650. Final work is generally done in the studio for more critical listening, of course, but sometimes I do have to deliver in a crunch from my portable rig, and my clients still pay me, thank goodness. I just am feeling like I can do better than the M4. But perhaps not!

You don't need low latency for mixing & mastering.

This is true for mixing and mastering, but as I mentioned, I also do music production, in which case low latency is critical for my workflow. If I was just mixing, then no problem with higher latency, 100% agreed.

That's one reason why I've more or less ruled out the Topping E2x2, which has good headphone outs, but which also has relatively poor latency from what I've read. (I'm also concerned with reports of reliability.)

Again, thank you for your feedback! It could be that I won't do much better than the MOTU M4! I definitely believe in confirmation bias, and it's entirely possible that is a factor in what I am experiencing.

 

[designfx]

Just for more clarification, this is for my portable music production rig for use with Sennheiser HD 600 650 6XX headphones -- I use an RME Fireface UFX III as my main studio interface, with professional studio monitors in an acoustically treated space (I failed to mention the monitors in my initial post, apologies if it made my post confusing).

 

[LTig]

If the M4 pro's phone output has significant output impedance plugging in a headphone can change the frequency response depending on the impedance curve of the phone - usually more lows than highs. To circumvent this you could add a separate analog headphone amp with low output impedance (and also higher output voltage) and insert it between the M4 and the headphone.

 

[masterhw]

I bought the MOTU M4 in part because of recommendations from this forum for portable use, but I'm just not loving the headphone out of the M4. I feel like it is not giving me what I need for the Sennheisers. It's not clear enough to me... and I've cross-checked this with another M4 on another system to confirm it's not my unit. Don't get me wrong... the MOTU M4 is not BAD. It's just not.... great. I feel like it's missing something and I get more out of the RME.

Following this thread as I've actually come to a similar conclusion, and while my M2 measures great and I can't find any technical flaw it just doesn't sound as good as my Fosi DS2 on HD 650s. I think the RME Babyface is their intended product for this use case, but it obviously clears your budget. Would love RME gear too but its not cheap, and they don't seem to have an obvious entry level model.

If the M4 pro's phone output has significant output impedance

It is allegedly 0.05 Ohm.

 

[designfx]

Following this thread as I've actually come to a similar conclusion

Maybe I'm not losing my mind then!

you could add a separate analog headphone amp

Thank you, definitely considering it! I would prefer a self-contained unit, if possible, but I'm open to it. I'm just not thrilled with this M4 headphone out.

I'm almost tempted to just buy several different audio interfaces and test them myself subjectively. I know that's not scientific, and I'm not ignoring the numbers. But I'm starting to believe there is just some disconnect IMO between the raw numbers presented by very competent reviewers like Julian Krauss, and the actual subjective experience of listening to complex music material.

On paper, the M4 headphone out should sound better than it does. Again, I'm not rejecting the numbers or scientific analysis, but I'm starting to believe that something is being missed in the reviews when it comes to just using test tones rather than also including complex material in the analysis. Perhaps the testing methodology doesn't account for some additional factor, perhaps distortion under load with complex material, wide transient behavior, dynamics, etc., that might not be so apparent with typical test sweeps, etc... Forgive me if I'm way off base here, but notwithstanding my acceptance of possible confirmation bias, I'm just not happy with the M4 headphone out. Hence why I'm here.

 

[LTig]

Forgive me if I'm way off base here,

As far as the known scientific research has shown, you are.

but notwithstanding my acceptance of possible confirmation bias, I'm just not happy with the M4 headphone out. Hence why I'm here.

First do a level matched blind test between the M4 and the UFX III (you'll need assistance and a volt meter) to make sure that there really is an audible difference. If there is one repeat with each candidate. Otherwise you may end up with something more expensive which is not better but sounds better just for you.

Doing a controlled test is very revealing and changes your mind in a positive way.

 

[designfx]

Quick follow-up, after a semi-casual blind test with the UFX III and the M4, I have confirmed my feelings about the M4 headphone out. We did NOT have a volt meter handy, so we did the best we could to level match. Obviously this is not scientific, and any listening test is going to be subjective by definition. Take my opinion for what it is. For me, the test was good enough, and I don't expect anyone to take my highly subjective opinion to heart. I'm not claiming any ASR-level precision in our testing. But even accounting for slightly different levels, we both felt the RME sounded better.

The M4 is not bad, as I mentioned before, but it's inferior IMO for some critical headphone mixing tasks. I felt there was a clarity missing specifically in the mid-high range with certain fast-transient sounds, making it more difficult to make mixing decisions in that range. I also felt the low frequencies were not quite as focused. The natural roll off of the HD 600 and 650 don't help matters of course, but nevertheless, working in that range is slightly more difficult IMO. Again, all opinion, and you might feel completely differently if you ran the same test.

I appreciate the suggestion to do a blind test BTW, it is indeed helpful. I think everyone should do it when in question, you might come up with different conclusions for your own needs, which will be different than my needs.

In any case, I'm now planning on picking up some different semi-portable interfaces and subjectively testing them against the M4. At least I have a better idea of what to focus on while testing, so hopefully I'll find a better solution than the M4. In the end, I realize I may not find a better solution though... since of course it's not quite fair to compare a bus-powered $270 interface to an interface that costs 10X+ as much with a much better power supply.

 

[Multicore]

MOTU M4 introduces significant noise in the mic inputs when you use its headphone amp. For good recording performance keep the headphone volume knob at zero. Demonstrated in the video below with an M2 starting at 41:30. I confirmed it myself by testing my own M4.

 

[designfx]

MOTU M4 introduces significant noise in the mic inputs when you use its headphone amp.

Yikes. Thanks for reminding me of this. Yes, this is unfortunate. I saw this video and made a note to keep the headphone knob at zero during recording, but I completely forgot about it. Now I'm a little frustrated TBH since I have some recordings that might have benefited from remembering this. And also, that's not possible all the time, since one often needs to have the headphone amp while recording.

So now I'm honestly leaning to saying goodbye to the M4. Given my subjective perception of the headphone amp reinforced with my blind test, plus this mic noise issue, I think it's probably time I move on. Assuming I can find a better device with a better headphone amp in my price range.

Thanks again.

 

[Multicore]

So now I'm honestly leaning to saying goodbye to the M4.

Given the importance of monitoring while recording I think this flaw in the MOTU M2 and 4 is disqualifying. I wonder if the M6 has the same.

 

[Evgenioni]

MOTU M4 introduces significant noise in the mic inputs when you use its headphone amp. For good recording performance keep the headphone volume knob at zero. Demonstrated in the video below with an M2 starting at 41:30. I confirmed it myself by testing my own M4.

This guy has problems with USB power. The problems that he “noticed” testify to this.

 

[kemmler3D]

Fwiw I have an M2 interface and for no particular reason other than vague doubts I use a JDS Atom amp with it. IMO it really lives up to the idea of "straight wire with gain". Another box isn't really super "portable" but it's smaller than the M4 anyway. And much cheaper than most of the alternatives mentioned ITT.

 

[designfx]

Given the importance of monitoring while recording I think this flaw in the MOTU M2 and 4 is disqualifying. I wonder if the M6 has the same.

Would be great if @amirm could add this to his review, which is excellent BTW - https://www.audiosciencereview.com/forum/index.php?threads/motu-m6-audio-interface-review.62578/

 

[designfx]

This guy has problems with USB power. The problems that he “noticed” testify to this.

The Youtube review has a comment in it that is very interesting to me. A user by the name of joeljaemaa9586 says:

"From an engineering standpoint, the headphone output level to mic input distortion correlation is probably caused by a non-optimal internal power supply design. Small interfaces like this often use internal boost-buck converters to step up the voltage coming from the USB or some other data link interface to a higher, dual polarity supply, usually +15V and -15V. These power rails are often used in common by all the analog audio circuitry, so both the headphone amp and mic inputs are internally run from the same power rails. When the headphone amplifier output is delivering a high amount of current into the headphones, this can cause the common power supply voltage to "sag" and drop below +-15V, causing the mic preamps to clip earlier because now their signal can't swing the entire voltage range that it was designed to."

 

[Multicore]

Would be great if @amirm could add this to his review, which is excellent BTW - https://www.audiosciencereview.com/forum/index.php?threads/motu-m6-audio-interface-review.62578/

Yes, it would but I think that ship has sailed. M6 uses a 15V 0.5A power supply and so may not exhibit the same pathology, or as badly.

 

[Pasarski]

You should consider Topping. I've been enjoying my E2x2 (I have the OTG version) a lot. Plenty of juice to drive any headphone and the preamps are quiet and linear.

 

[Evgenioni]

The Youtube review has a comment in it that is very interesting to me. A user by the name of joeljaemaa9586 says:

"From an engineering standpoint, the headphone output level to mic input distortion correlation is probably caused by a non-optimal internal power supply design. Small interfaces like this often use internal boost-buck converters to step up the voltage coming from the USB or some other data link interface to a higher, dual polarity supply, usually +15V and -15V. These power rails are often used in common by all the analog audio circuitry, so both the headphone amp and mic inputs are internally run from the same power rails. When the headphone amplifier output is delivering a high amount of current into the headphones, this can cause the common power supply voltage to "sag" and drop below +-15V, causing the mic preamps to clip earlier because now their signal can't swing the entire voltage range that it was designed to."

I had Motu M2 rev1, I did not face such problems
I recorded on a microphone Townsend Lab L22 and used headphones DT770 80Ohm. There were no problems with power and noise.
Today there are more interesting interfaces. Yes, I like Topping

 

[designfx]

Fwiw I have an M2 interface and for no particular reason other than vague doubts I use a JDS Atom amp with it.

You should consider Topping. I've been enjoying my E2x2 (I have the OTG version) a lot.

Thank you both, will check them out. I'm still most likely going to say goodbye to the M4, but I haven't had time to subjectively test other interfaces yet, so I am keeping all my options open. An external headphone amp is definitely on the table though.

BTW, on further thought about my personal opinion/experience with the headphone amp on the M4, my perception of the headphone amp might have a real basis tied to this whole distortion issue brought up in that Youtube video mentioned by @Multicore. After further reflection (and thinking about the comment by joeljaemaa9586), I just looked at my M4 right now, and I noticed the gain is up on both mic preamps, which are connected to microphones ( +both with 48v switch engaged), even though the actual inputs are muted in my DAW (on laptop no less). Gain is up on output too. Apparently I never really paid attention to this.... but it's full features are activated and powered.

So perhaps that all might be part of my situation. With gain + 48v going to both mic preamps PLUS mains PLUS the headphone amp, all that together might lower the performance of the headphone amp in terms of available current. Maybe? I have no idea if that's the case, and don't have time to properly test, but it is now more clear to me than ever that USB power is really a limiting factor on a lot of these bus-powered devices. It's amazing what they have accomplished with so little current, but maybe I've been pushing too close to the edge to expect some of my USB-powered devices to perform optimally under max usage conditions. Perhaps the MOTU M4 might not have enough current to drive all of that at the rated (and measured) specs, which might result in suboptimal performance in more than one area?

In any case, I'm still planning on testing some more options and I'll figure out a new plan. Thank you all for your thoughts! I really appreciate this forum for the depth of insight on the technical side.