How much does audio interface really matter?

Chelonian

Member
I want to get back to audio recording and have an old M-Audio Firewire Solo but no Firewire card. I had thought that it is so old that today's interfaces could give a much better sound quality for music recording, but now I am not so sure.

I want to do home music recording of all sorts, including some quiet acoustic guitar and singing (with lots of quiet or silent sections), so limiting noise in the recordings is important. I also hope to try some effects on the computer for guitar so low latency would probably also be good.

But will buying a newer interface really matter that much? If so, I need to see some quantification about it.

Also, I could get a Behringer UM2 for about $40 or a MOTU M2 for about $170. Sure, the MOTU has a nice digital display and a power-off button, but really they do the same thing. Will I be able to hear the noise floor differences, or will the latency differences matter, between these two boxes?

Basically, I need to understand how much noise floor, latency, distortion, and other audio effects are acceptable for my purposes. But I don't know how to go about ascertaining that. I have watched quite a few Julian Krause videos, and he gives numbers (such as in his video for a "preamp shootout," showing noise floors from -120 dB to -130 dB), but I don't know what is a reasonable cutoff for quality, a point beyond which it is just a waste of money to upgrade.
 
I recommend you read through this thread, and go to Sweetwater's website and download the Hi Res audio files and compare. They compared 9 different audio interfaces under $500

Sweetwater Interface comparison - Under $500

I found that the variations in performance between the vocal and acoustic guitar samples varied FAR more than the interfaces. The reamped electric guitar and piano recordings used the same mic and performance. I would listen to those tests, leaving the vocal tests and acoustic tests out.

As for latency, etc, that's going to vary based on your computer's ability, as well as the drivers. RME and MOTU are supposed to have good solid drivers, but many work just fine with pretty low latency. If you do direct monitoring, it almost becomes a non issue.

Regarding noise floor, I doubt most people can tell the difference between 120 and 130dB unless they just record a ridiculously low level and then pump it up artificially. A CD only has about 90dB potential, so if you go 24 bit, you're getting better than CD performance. Even most mics, if they have a self noise of 10-15dB and a max SPL of 135dB is only giving you a S/N of 120dB.
 
It used to matter a lot. It doesn’t anymore. Just get something that doesn’t have a high failure rate. I’ve yet to see a Behringer interface fail.
 
Whilst it is true that 'converters' are very similar in their (high) performance there is more to an interface than converters.

Yes, the basic Berry's give good sound. I had a UMC204HD for a week or two, very good, even has very useful pre amps. Passed it onto son and he is very happy with it. But, I would suggest you do not go below the 204HD in price. Less than that the interfaces do not have ASIO drivers (not even sure the 204's are that good!) and you will forever have latency problems with other than ASIO.

A good 2 in 2 out interface can be had from the 'other' top makers. MOTU, Steinberg, NI*, Focusrite, Tascam, Zoom, Presonus, Audient. I strongly suggest you get one with MIDI ports but others differ.

However, a step up is an AI with two mic/line/instrument inputs plus two more line inputs (4 outputs is also handy). Such an AI is a bit future proof as you can connect other gear such as a synth, drum machine or indeed a mixer of any track count and have a stereo mixdown plus the two mic channels. Such an interface is the NI Komplete Audio 6 Mkll. I have a Mk1. IF I were in the market again I would go for the MOTU M4. The 'numbers' are at the edge of what is physically possible,i.e. 'king good!

So, to recap...Yes, you CAN buy a very cheap AI that will sound AS good as a CD player but think long, save a bit and READ a lot!

Dave. *nothing wrong with my KA6 I would just LIKE an M4! (get thee....)
 
[MENTION=205046]Chelonian[/MENTION] - as others note, especially in "consumer" models you can assume there's a lot of minor differences, but if you read reviews, you'll find little quibbles about the sound quality. Features like LEDs, an extra headphone output or heapdhone level, hardware quality/durability, driver and installation issues, etc. are the things that differentiate to a large degree. Things like whether it has sample rates of 192kHz (or 384!!) should not be a concern.

Firewire is no longer supported and even Macs no longer have a physical port or support, though they'll be happy to sell you an adapter and let you try to see if it works. (Presumably it was still in the OS/core audio, but it may be completely gone as of Catalina and certainly I'd assume Big Sur probably snipped it out.)

The Motu M2 gets a lot of love in a couple online/YouTube reviews - basically nails all the specs of anything close in price. (Podcastage and Julian Krause are two reviewers that come to mind.) If it's in your budget, I would certainly consider that over the UM2. The Behringer model [MENTION=89697]ecc83[/MENTION] mentions is well liked for its value.

Here's a link to a Julian Krause review (Audient iD14) where he has a comparison of actual test specs of several interfaces. I've set the start point at that table, so you'll want to full-screen and pause to review it, but watch the whole thing to see how he does a review.

Audient iD14 USB Audio Interface Review (audio performance measured) - YouTube
 
[MENTION=205046]Chelonian[/MENTION] - as others note, especially in "consumer" models you can assume there's a lot of minor differences, but if you read reviews, you'll find little quibbles about the sound quality. Features like LEDs, an extra headphone output or heapdhone level, hardware quality/durability, driver and installation issues, etc. are the things that differentiate to a large degree. Things like whether it has sample rates of 192kHz (or 384!!) should not be a concern....

...The Motu M2 gets a lot of love in a couple online/YouTube reviews - basically nails all the specs of anything close in price. (Podcastage and Julian Krause are two reviewers that come to mind.) If it's in your budget, I would certainly consider that over the UM2. The Behringer model [MENTION=89697]ecc83[/MENTION] mentions is well liked for its value.

Thank you. Can you say why you would certainly consider the MOTU M2 over the Behringer UM2 given the price difference is $130?
 
Thank you. Can you say why you would certainly consider the MOTU M2 over the Behringer UM2 given the price difference is $130?

MOTU has been a respected company for interfaces for a long time. Behringer has not, but a lot of good engineers have gone to Behringer. Their new stuff is good.
 
Thank you. Can you say why you would certainly consider the MOTU M2 over the Behringer UM2 given the price difference is $130?
On a feature comparison, the MOTU M2 vs. UM2 is not the right one to look at, as it is slots in somewhere between the Behringer UMC202HD (no MIDI) or UMC204HD (more outputs).

I just suggested the UM2 because it gives you a single input at the lowest cost, and spec-wise, is a better option than buying a cheap USB mixer, for instance. But, it's limited. The M2 has better specs, but as I would argue, mostly those differences are not going to be the thing that makes/breaks your first home recordings. Not having an interface at all, of course, keeps you from getting started!

In the end spending some time thinking about what you think you'd like to do in say the next 2 years is not wasted time. But, you have to balance for yourself the scales of budget vs. dreams vs. actually doing something. (I think a 2 channel interface is a good place to start, though.)
 
I’m still using a FireWire card for one of my interfaces because it sound nice and has inputs and outputs in the right place for me. I simply do not subscribe to all the wonder and embellishment some interfaces generate. I understand some people hear and love certain audio waveform modifications that electronics can do. Colouration it used to be called. Back in the early digital days it was bad, now, it’s marketed as a plus. We wont ever all agree now, that’s fine.

I think there are no terribly performing ones any more. Public opinion kills them off.

For me they have two features that are important. Low noise and gain, which often annoy each other. Loads is always said that certain mics need more gain, but practically I have enough mics that gain is never an issue for me.

The killer for old interfaces though, is drivers. Will an old interface actually work? Sadly my store has a few interfaces in it that don’t work any longer. Six years is a long time for computer drivers. Ten years is antique. Why would a manufacturer write new drivers for old products? There’s no business reason to do it.

Before you spend ten quid on a FireWire card, check you can still get the windows 10 drivers. It’s a shock to have to pension off a perfectly decent interface because it’s no longer supported.
 
Take Rob's comments to heart. You could probably get a PCIe FWire card to run an AI but there are pitfalls even there.
Since Fwire is essentially obsolete such a card may not work with any particular mother board and Win 10.
The next trap is the FW controller chip. Yonks ago only the Texas Instruments chip was 'usually' the only one that had a chance of working but even there some FW AIs were even fussier and needed another brand.

A decade or so ago the forums were deluged with weeping folk who had bought a FW interface and could not get it working on THEIR PC. The problem was even worse for laptops where you cannot change the controller chip.

Me? I would just bend the flexible friend and buy RME and sit back in the almost certain knowledge I would be safe till around 2030!

Dave.
 
On a feature comparison, the MOTU M2 vs. UM2 is not the right one to look at, as it is slots in somewhere between the Behringer UMC202HD (no MIDI) or UMC204HD (more outputs).

I just suggested the UM2 because it gives you a single input at the lowest cost, and spec-wise, is a better option than buying a cheap USB mixer, for instance. But, it's limited. The M2 has better specs, but as I would argue, mostly those differences are not going to be the thing that makes/breaks your first home recordings. Not having an interface at all, of course, keeps you from getting started!

In the end spending some time thinking about what you think you'd like to do in say the next 2 years is not wasted time. But, you have to balance for yourself the scales of budget vs. dreams vs. actually doing something. (I think a 2 channel interface is a good place to start, though.)

What I want to do within the next 2 years is make good quality recordings. I have two dynamic mics and one condenser mic (the Blue Spark). I want to be able to record quiet things (maybe even electric guitar unamplified, tapping on a desk, etc.) and not have there be noticeable hiss in the background of the recording. I have no need for more than two inputs at a time (like acoustic guitar and vocals) and likely never will (and I think the UM2 can do that). I have no idea if I will ever use MIDI as I know nothing about that, plus I assume I can plug keyboards into the line-in of any of these things.

I just don't want to pay $130 more for "coolness"--for a name like Mark of the Unicorn and rainbow meters on a black box. If the meters are going to matter to my recording quality, sure, that could be a reason to buy a MOTU M2. I could see that, but I also think maybe I can just use meters in the software on my computer? Or if the better noise floor, dynamic range, or headphone amps are going to matter to the recording quality or even the ease of recording, then maybe $130 spread over the next decade of use is a no brainer. I just don't know at all at this point and hate spending money uselessly.

There's also the issue of the bundled software. If I buy a Focusrite vs. the Behringer UM2 vs. the MOTU M2 is the software I get with it going to make a big difference? Can I get comparable software for free or cheap elsewhere? Etc.

Another thing that concerns me about the Behringer UM2 is that apparently the drivers for Windows (7-10?) on Behringer's site don't work with it and you have to find it elsewhere online. That does not speak well for the company. Yet I am also seeing many examples of the MOTU M2 just suddenly stop working after a few weeks--though I am also seeing the MOTU company being responsive about getting those customers a new one.
 
What I want to do within the next 2 years is make good quality recordings. I have two dynamic mics and one condenser mic (the Blue Spark). I want to be able to record quiet things (maybe even electric guitar unamplified, tapping on a desk, etc.) and not have there be noticeable hiss in the background of the recording. I have no need for more than two inputs at a time (like acoustic guitar and vocals) and likely never will (and I think the UM2 can do that). I have no idea if I will ever use MIDI as I know nothing about that, plus I assume I can plug keyboards into the line-in of any of these things.

I just don't want to pay $130 more for "coolness"--for a name like Mark of the Unicorn and rainbow meters on a black box. If the meters are going to matter to my recording quality, sure, that could be a reason to buy a MOTU M2. I could see that, but I also think maybe I can just use meters in the software on my computer? Or if the better noise floor, dynamic range, or headphone amps are going to matter to the recording quality or even the ease of recording, then maybe $130 spread over the next decade of use is a no brainer. I just don't know at all at this point and hate spending money uselessly.

There's also the issue of the bundled software. If I buy a Focusrite vs. the Behringer UM2 vs. the MOTU M2 is the software I get with it going to make a big difference? Can I get comparable software for free or cheap elsewhere? Etc.

Another thing that concerns me about the Behringer UM2 is that apparently the drivers for Windows (7-10?) on Behringer's site don't work with it and you have to find it elsewhere online. That does not speak well for the company. Yet I am also seeing many examples of the MOTU M2 just suddenly stop working after a few weeks--though I am also seeing the MOTU company being responsive about getting those customers a new one.

The Behringer is fine. There was a shootout Sweetwater did comparing 5 interfaces under $250 I think and nobody could tell you what was what if they were blindfolded. I would suggest the 202, though, rather than the UM2. The part about software depends on whether you will use it, but you can find a lot of good, free solutions. Behringer provides an Asio4All driver, which will work with the interface.
 
What I want to do within the next 2 years is make good quality recordings. I have two dynamic mics and one condenser mic (the Blue Spark). I want to be able to record quiet things (maybe even electric guitar unamplified, tapping on a desk, etc.) and not have there be noticeable hiss in the background of the recording. I have no need for more than two inputs at a time (like acoustic guitar and vocals) and likely never will (and I think the UM2 can do that). I have no idea if I will ever use MIDI as I know nothing about that, plus I assume I can plug keyboards into the line-in of any of these things.

I just don't want to pay $130 more for "coolness"--for a name like Mark of the Unicorn and rainbow meters on a black box. If the meters are going to matter to my recording quality, sure, that could be a reason to buy a MOTU M2. I could see that, but I also think maybe I can just use meters in the software on my computer? Or if the better noise floor, dynamic range, or headphone amps are going to matter to the recording quality or even the ease of recording, then maybe $130 spread over the next decade of use is a no brainer. I just don't know at all at this point and hate spending money uselessly.

There's also the issue of the bundled software. If I buy a Focusrite vs. the Behringer UM2 vs. the MOTU M2 is the software I get with it going to make a big difference? Can I get comparable software for free or cheap elsewhere? Etc.

Another thing that concerns me about the Behringer UM2 is that apparently the drivers for Windows (7-10?) on Behringer's site don't work with it and you have to find it elsewhere online. That does not speak well for the company. Yet I am also seeing many examples of the MOTU M2 just suddenly stop working after a few weeks--though I am also seeing the MOTU company being responsive about getting those customers a new one.
If you want to put a mic (each) on the acoustic guitar and vocal at the same time, you need 2 mic preamps. The UM2 does not have that. You could plug in an electric guitar or acoustic-electric, but it would not sound as natural as a mic'd acoustic guitar.

Short story is that there are going to be some disappointed buyers of every single one of these because they are not as simple to use as a smartphone.

But, they're all companies that have been around for a while and are in the business, i.e., these companies are all competing for the same customers, so you can figure these kinds of interfaces are largely commodities, i.e., you get what you pay for, and there's really not much "snob appeal" $ built into a sub $200 interface.

Now, I think Behringer has achieved a good degree of hardware reliability and the days of folks dismissing it as something that will just fall apart quickly are history. You may get a few less marketing dollars, though I suspect that's a "per capita" kind of thing, because they probably have a bigger budget than MOTU, just a lot more products. And support is always a question. Go download manuals and specs for their products and then do the same for others you are considering. See how many driver updates have been posted, etc. The money you pay goes somewhere, but on a physical box comparison, the differences come down to small numbers, though there's no discounting the fact that some of the numbers are audible. If you want to record quiet, acoustic stuff, you'll want low noise specs and a low, self noise condenser, at least IMO. (If the preamp has sufficient clean gain, though your dynamic mic will have the lowest noise.)

I don't discount LEDs. I like the ones on my old Saffire Pro, and miss them on the new Steinberg. It's easier to set levels as a self recorder when I can reach over to the interface and turn the knob and watch a bouncing, stacked LED display, vs. trying to read the numbers or display on the computer screen that's a couple feet further away. But, that's me.

For software, just budget for the paid version of Reaper is my suggestion. It's got a huge user community and the cheapest, full featured DAW around.
 
Honestly the Behringer UM2 isn't a very good interface. You would definitely bump into its shortcomings. It uses Behringer's Xenyx preamp, which is a relatively noisy thing compared to their Midas preamps that the UM2's bigger brothers all use. It only has RCA outputs, so you lose the ability to use balanced connections to minimize interference picked up along your cable runs in your room. It doesn't have its own Windows drivers so you're stuck with the limitations of ASIO4ALL. It only records a 16-bit depth from the inputs, which limits your dynamic range and makes it a bit more difficult to get your gain staging right. And the headphone output isn't going to drive higher impedance headphones.

The M2 has 2 combo XLR/TRS/TS mic/line/inst inputs and very good noise and distortion statistics (take a look at Julian Krause's YouTube page for some really in-depth comparisons between various interfaces' specs and performance). The M2 has good stable Windows drivers, very good input latency, "just ok" output latency, records at a 24-bit depth from the inputs, has a best-in-class headphone DAC that can drive higher impedance headphones with ample volume, has balanced outputs, and a solid-feeling build quality. And of course there's the very attractive input AND output metering.

I don't think that it's a fair fight between the UM2 and the M2. Behringer does have better interfaces in their U-Phoria line once you step up to their UMC "HD" models. Then you get dedicated Windows ASIO drivers. And they offer features that nobody else does in this price range: inserts on each channel and a switchable -20 dB pad on each channel. The features-per-dollar of the HD interfaces is outstanding.

As far as sound quality, you would notice a difference between the UM2 and the M2. The preamps, converters, and headphone output quality on the M2 are actually noticeably better. Less so between the UMC HD interfaces and the M2, but the M2 still has a stronger, flatter, distortion-free output compared to the UMC.

For the most part, though, the whole purpose of integrated preamps on these entry-level interfaces is to be clean and noise-free. Same for the converters (they mostly all use the same converters). Almost all of them accomplish this. The differences in sound once you get above the UM2 are very subtle, but they're there. Focusrite has just a hint of "air" to their preamps (even the ones without the Air option). The SSL 2+ has a bit of its own midrange character, even without the 4K switch enabled. The M2/M4 is clean and articulate. The Roland Rubix is very flat and therefore kind of boring sounding. Behri's Midas preamps are nice and flat.

But NONE of these very subtle differences are going to make or break your home recordings. If the inputs have enough gain and enough headroom and aren't noisy, then they won't stand in your way to get your ideas persisted to your computer.
 
If you want to put a mic (each) on the acoustic guitar and vocal at the same time, you need 2 mic preamps. The UM2 does not have that. You could plug in an electric guitar or acoustic-electric, but it would not sound as natural as a mic'd acoustic guitar.

I realized I have a microphone mixer as well (I got for free and have never used). It accepts four "balanced Lo Z Mic in" and provides one XLR out. It's a Mini-Mix 4 Microphones Input Model BWK-II.

Would I be able to use that to record singing + acoustic guitar with two mics in this way and have it be good?
 
Would I be able to use that to record singing + acoustic guitar with two mics in this way and have it be good?

You then have to be able to get the mix of voice and guitar exactly right, because with one XLR out you only get one mixed output to go to the interface. You cannot separate voice and guitar remix afterwards.
 
Thanks for this helpful info! (to everyone in this thread, too!).

Honestly the Behringer UM2 isn't a very good interface. You would definitely bump into its shortcomings. It uses Behringer's Xenyx preamp, which is a relatively noisy thing compared to their Midas preamps that the UM2's bigger brothers all use.

I'm a bit confused. Julian Krause measured the noise floor of the UM2 interface vs. the UMC22 and it was this:

- UM2: -127.2 dBU
- UMC22: -127.9 dBU

To me, that's indistinguishable. Am I missing something?

> It only has RCA outputs, so you lose the ability to use balanced connections to minimize interference picked up along your cable runs in your room. It doesn't have its own Windows drivers so you're stuck with the limitations of ASIO4ALL. It only records a 16-bit depth from the inputs, which limits your dynamic range and makes it a bit more difficult to get your gain staging right. And the headphone output isn't going to drive higher impedance headphones.

All useful intel. How much will 16-bit limit the dynamic range? And I have no idea what you mean by "get your gain staging right."

As far as sound quality, you would notice a difference between the UM2 and the M2. The preamps, converters, and headphone output quality on the M2 are actually noticeably better.

I'm starting to wonder if converters really matter much if at all. Ethan Winer has various tests on his page that show indistinguishable recordings as converted through various converters--including a $25 Soundblaster card (indistinguishable recordings from those converted through a $6000 Apogee interface--same preamp used).
 
I'm a bit confused. Julian Krause measured the noise floor of the UM2 interface vs. the UMC22 and it was this:

- UM2: -127.2 dBU
- UMC22: -127.9 dBU

To me, that's indistinguishable. Am I missing something?

If those are the numbers that he came up with, I trust it. But I'm not sure if those are with the gain at 100% on both interfaces, or 0%, or somewhere inbetween. I'm actually surprised at those figures. My experience with the Xenyx preamps are on Behri's mixers, and while they're not extremely noisy, they just don't have a ton of usable gain before they get conspicuously noisy and/or distorted. At least, that was the case with the Behri mixer I've used.

I've got 8 of the Midas designed preamps in my ADA8200 and those things are solid. I'm pretty impressed with them, so I really like the U-Phoria interfaces that use them (I've used the UMC22 and the UMC404HD personally).

All useful intel. How much will 16-bit limit the dynamic range? And I have no idea what you mean by "get your gain staging right."

A 16-bit depth has a dynamic range of about 96 dB (which is nothing to sneeze at) but a 24-bit depth has a dynamic range of about 144 dB, which is pretty huge. It makes setting your gain to a setting of "loud enough to overcome the noise floor, but not loud enough to clip" almost a no-brainer. The wiggle room is huge, so it takes a lot of the stress out of setting your gain. That's pretty much the "trick" to gain staging: getting your signal level into an ideal range at each spot where you have control over it.

I'm starting to wonder if converters really matter much if at all. Ethan Winer has various tests on his page that show indistinguishable recordings as converted through various converters--including a $25 Soundblaster card (indistinguishable recordings from those converted through a $6000 Apogee interface--same preamp used).

Yeah, if there's anything to put near the end of your list of things to worry about in your home studio, converter quality would be near the bottom. And that's not because they're not important (they're the single thing making analog waveforms into digital information, and vice versa...which is essential to recording onto a computer) but more because converters are of generally great quality at this point. I think that the main difference is how high of a sample rate they can achieve, and how steady the clock is that they're working with. As an experiment, you can record audio to two different interfaces/recorders over a long period of time, and they'll eventually start to drift apart in timing. Higher quality converters will be more steady. At least that's the one instance that I've noticed converters behaving differently. I'm a little skeptical that a Sound Blaster would be indistinguishable from an Apogee, but I'll reserve judgement until I've watched Ethan's content on the subject. I'd like to hear a null test between the two signals to see if they're truly identical or not.

Anyways, it's a great time in history to be shopping for an interface. Even the UM2 that I kinda rag on is a good interface when compared to what was available 15 or 20 years ago. And at that price point, it's in a class of it's own on today's market. It's pretty much only competing with no-name USB dongles or Behri's other interfaces that don't have integrated preamps like the UCA series. But after having used several entry-level interfaces from (almost) all of the major brands, I'd say to do yourself the favor of getting one that has dedicated ASIO drivers if you're recording on Windows. That'd rule out the UM2, UMC22, UMC202, and anything in the U-Phoria line without the "HD" in its model name.
 
"- UM2: -127.2 dBU
- UMC22: -127.9 dBU"

Well, "I" don't trust those figures Tads! An NE5532 (and I doubt Berrys are using better) configured as a unity gain follower has a noise output of about -120dBu, any gain will worsen that proportionally. A dynamic range of 120dB is about that of the top end interfaces and only a handful better it and then only by a dB or two.

I do agree that converters and pre amps have come on shedloads in ten years and yes, the noob need not worry much about them. FAR more important (for musical purposes) are TWO mic channels and ASIO drivers.

After that you are paying for more channels, even better drivers (lower latency) bit more controllable mic gain, digital gain and DSP.

One manufacturer stands out who has eschewed 'built in obsolescence' and that is RME.

Upon post cup o Joe reflection, those numbers could be for the EIN* of the mic pre amps at some optimized gain but the noise OUTPUT will be vastly greater.

*That is a measure of how much noise the amplifier adds to the noise of a source resistor, usually taken as 150 Ohms and is around -130dBu over a 22kHz bandwidth so -127dBu is very good and bettered by only a very few specialized pre amps. (I still don't believe it!)

Dave.
 
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"- UM2: -127.2 dBU
- UMC22: -127.9 dBU"

Well, "I" don't trust those figures Tads! An NE5532 (and I doubt Berrys are using better) configured as a unity gain follower has a noise output of about -120dBu, any gain will worsen that proportionally. A dynamic range of 120dB is about that of the top end interfaces and only a handful better it and then only by a dB or two.

I do agree that converters and pre amps have come on shedloads in ten years and yes, the noob need not worry much about them. FAR more important (for musical purposes) are TWO mic channels and ASIO drivers.

After that you are paying for more channels, even better drivers (lower latency) bit more controllable mic gain, digital gain and DSP.

One manufacturer stands out who has eschewed 'built in obsolescence' and that is RME.

Upon post cup o Joe reflection, those numbers could be for the EIN* of the mic pre amps at some optimized gain but the noise OUTPUT will be vastly greater.

*That is a measure of how much noise the amplifier adds to the noise of a source resistor, usually taken as 150 Ohms and is around -130dBu over a 22kHz bandwidth so -127dBu is very good and bettered by only a very few specialized pre amps. (I still don't believe it!)

Dave.
Julian Krause has one or two videos on how he does the noise measurement with the XLR plug and 150Ω resistor (I think that varies depending on what country you live in!). Regardless of whether his number is the same (as yours, for instance), he does use the same method for every interface and manufacturer, so in that sense they are, I would argue, all comparable. In some cases his measurements are pretty close to the manufacturer spec, too. But, maybe someone has figured out how to game the test measurement setup, like VW and their diesel engine emission kerfuffle (to put it mildly).
 
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