Ok, let's say anything better than a baseline 100$ interface is all placebo, well it may be chances are it is. But even if it is placebo, it will still be more pleasant to work with the interface you prefer even if it is all smoke and mirrors.
On a more practical level, features and implementation of those is more important. Wobbly buttons as the Audient above kills the experience.
I agree, but no one is really arguing this though..? Those going through great efforts to explain that it will sound identical are simply stating just that. It's been indisputably demonstrated that properly engineered $100 dacs/adcs/amps, even a $10 USB dongle has the ability to audibly transparent within its operational specifications, what you are paying for is power, features, implementation, aesthetics, build quality, brand name etc. Most of the time a majority of that cost is brand name and even conventionally reputable brands have an abundance of problems. That's a big reason why this site exists, to make consumers aware of issues with products and to make better informed purchase decisions based on the objective reality of audio science.
Personally, one thing I hate about the MOTU is the that mic inputs are on the front. I have one or two permanently connected microphones so this is annoying for me and causes extra clutter and makes my desktop surface not look as good, but it's something I obviously knew buying the product and a subjective problem- someone might love the convenience of the inputs at the front and consider it a feature. Similarly, if I had to drive demanding headphones with my MOTU I would not have gotten it, since the main reason for the purchase was specifically to have an all-in-one interface that could be used when traveling.
As for M.2, it has documented problems changing sample rate on Windows, that is a real problem and makes usage sometimes clumsy and un-intuitive. A problem most other interfaces do not have even a trace of.
I don't think I ever had this problem personally, when I first got it there was sometimes a brief silence when switching rates but I don't notice it anymore, perhaps it's fixed with a firmware update? Perhaps using it in exclusive mode/ASIO should not cause this?
Expounding further do you know what sounds different if two identical devices differ by .4 db? One sounds like it has more extension at both ends a deeper richer soundstage and just a better sound. It does not sound louder, it just sounds better. This is a widely known phenomenon. You need careful matching to avoid it. Using music and an SPL meter no matter how careful, you aren't going to get matching within .1 db which is what you need. You cannot educate or train yourself out of it or around it. You just cannot do it.
The ~0.3-0.4 dB rolloff (and only 0.1-0.2 dB at ~35-40hz) at such a narrow band deep into sub bass is hardly audible with test tones let alone with music that dips that low, never mind with the 99%+ of music that does not even have any spectral content or psychoacoustically unmasked content in these octaves to begin with. Sub bass minimally affects sound localisation and in fact, deters from it at worse. Most sub bass is not even stereo mixed. A tiny bass rolloff simply explains none of the "soundstage" claims in this thread even if they were matched! It would be nice if it was more ruler perfect like other products, but it outshines comparable products in virtually every other metric to the point where this shortcoming is virtually meaningless. As you said none of the "obvious" psychoacoustic effects these people claim to be hearing between the two interfaces would even be remotely explained by such a deviation, and they aren't even accurately volume matching, so in my view whatever claims are simply nonsensical.
Ok. Got the two side by side. And Ive test it with my eyes closed and I have to state that the Id14 it is much more musical than the M2. It´s like it is more 3D sounding, the soundstage is much clearer and open.
It will be dificult to make a sound test to prove this but I can try with my field recorder.
Regards headphone output I prefer the M2, sounds really good, warm and musical, good sound stage. The ID14 in this case, sounds colder, less sound stage.
Regards construction the M2 is rock solid. The new Id14 mk2 came with the volume pot a bit wobbly, it sucks. But I am returning the M2. I almost don´t mix with headphones.
Volume matching problems aside, what headphones did you use? I already showed data showing quite high output impedance on the ID14, so it is something that has to potential to change the FR of a headphone if it is low impedance, which already is yet another reason to invalidate informal tests of this nature. And even so, I definitely doubt this would affect the frequency response to a degree that the soundstage would sound clearly and indisputably more '3D'.
It's no meaning circle jerking around the issue, anyone interested in those interfaces should look at hardware features and quality of the OS-driver instead. And maybe output power of the headphone jack, if that is to be used. Much more important than perceived/imagined SQ.
Measurements of greater interest for a interface is noise level of the mic inputs as some mics have very weak output signal(Shure SM-7), that differs a lot between interfaces. Also a larger headroom lessens the risk of overdriving the inputs, it's a important figure. Lastly, some interfaces dont fare very well with High-Z sources like guitars and keyboards, that is a thing that needs to be checked.
SQ on the line outs is probably the least important quality of a interface as most/all sounds very good.
Gain and noise level of the front inputs are in the manufacturer spec sheet and noise is also confirmed by the 3rd party measurements I posted earlier, there are a number of youtube videos corroborating the measurements as well. Others have measured those outputs at various gain levels, even with output monitoring on and the mix dial at various settings the FR stays virtually the same (+/- ~0.1-0.2dB) throughout the audible band.
I use it with a SM7b regularly and have no issues. I threw a se dm1 dynamite on it since I had one laying around since I mostly use it for voice chatting at my desk and sometimes having the extra headroom is nice for adjustments on the fly since I speak at various distances and volumes throughout the day. If you are using it in any 'professional' recording capacity the interface alone is quite enough for similar gain hungry mics. Use it with a high-Z bass as well. I agree that more comprehensive measurements of the other inputs would be a nice asset. All the 3rd party measured specs are in line with the manufacturer ones so I'm inclined to believe whatever unmeasured claims from the manufacturer are believable.
