Choosing audio interface to suit AKG702

[iionas]

Hi guys and girls,

Long time reader first time poster.

A little background about me: I produce electronic music as a hobby and my current audio interface is on its way out and I would like to purchase one but I don't want to stuff around I'd like to get it right.


I have a pair of AKG702 which I have been using for the past 10 years, both for production and music playback and content creation / consumption. I'm happy with them I don't wish to change them. They are rated at 62ohms max 200mw.

Info taken from here: https://www.akg.com/Headphones/Professional Headphones/K702.html

I have been eyeing off these:

Motu ultralite mk5 - https://motu.com/en-us/products/gen5/ultralite-mk5/
Motu M6 - https://motu.com/en-us/products/m-series/m6/

I have also considered an Id44mkii however I know little to nothing about this company.

The output of the headphone jack on both of those units can be found here from the legend Julian Krause. Attached to the post.

I'm just wondering if someone could please explain to me if the headphone outputs of these two interfaces are enough for my headphones.

If not, am I better off grabbing the M6 and a headphone amp to suit?

Should I Ditch the akgs and grab a m6 and a new set of headphones instead?

My budget thus far is 650 euro.

The M6/mk5 has enough I/O for me, maybe a little overkill.

Thank you in advance and apologies if this seems very straightforward for some of you I'd like to learn and understand your
responses.

i look forward to replies!

Cheers

iionas

 

[staticV3]

Here's how much voltage/power your Amp needs to output at 62Ω for a given SPL with the K702:


You can use Krause's data to predict an interface's power/voltage output at 62Ω. Here's how:

Spoiler: How To

1. Copy his data into a spreadsheet like so (MOTU mk5 as an example):

2. Convert W to Vrms like so:

3. Copy only these values:

4. open mycurvefit.com, click Clear, then Fit Method -> Nonlinear -> 4PL, then click into the text box under X Axis Title, and paste via Ctrl+Shift+V.

5. click Next -> Next -> Apply and you'll see this:

6. go to Fit Method -> Nonlinear -> and click 5PL. Sometimes 4PL gives the best results, other times 5PL. Try both and see what works best.

7. once you're happy with the curve fit, click Predict, then Swap, then enter 62 under X Axis Title:

Now you can see that the mk5 will output about 2.23Vrms under 62Ω Load, or 2.23^2/62=0.080W=80mW.

Rinse and repeat for every interface that you're interested in.

To calculate the exact peak SPL that you can get with the K702, use the Vrms and do this: 104+20*log base 10(2.23)=111dB SPL Peak.

104 is the approximate sensitivity of the K702 in dB/Vrms, as you can see here:

And 2.23 is the max Vrms at 62Ω that we've predicted earlier.

 

[iionas]

Here's how much voltage/power your Amp needs to output at 62Ω for a given SPL with the K702:
View attachment 265253

You can use Krause's data to predict an interface's power/voltage output at 62Ω. Here's how:

Spoiler: How To

1. Copy his data into a spreadsheet like so (MOTU mk5 as an example):
View attachment 265262

2. Convert W to Vrms like so:
View attachment 265263
View attachment 265264

3. Copy only these values:
View attachment 265265

4. open mycurvefit.com, click Clear, then Fit Method -> Nonlinear -> 4PL, then click into the text box under X Axis Title, and paste via Ctrl+Shift+V.

5. click Next -> Next -> Apply and you'll see this:
View attachment 265266

6. go to Fit Method -> Nonlinear -> and click 5PL. Sometimes 4PL gives the best results, other times 5PL. Try both and see what works best.
View attachment 265267

7. once you're happy with the curve fit, click Predict, then Swap, then enter 62 under X Axis Title:
View attachment 265268

Now you can see that the mk5 will output about 2.23Vrms under 62Ω Load, or 2.23^2/62=0.080W=80mW.

Rinse and repeat for every interface that you're interested in.

To calculate the exact peak SPL that you can get with the K702, use the Vrms and do this: 104+20*log base 10(2.23)=111dB SPL Peak.

104 is the approximate sensitivity of the K702 in dB/Vrms, as you can see here:
View attachment 265272
And 2.23 is the max Vrms at 62Ω that we've predicted earlier.

hey mate thats absolutely bloody amazing work.

Thank you so much that helps me a bit.

The way i understand the calculations is that these will be powered but wont be enough to saturate and actually get the full potential out of them.

 

[kemmler3D]

FWIW I have the MOTU M2 using with both Mac and Windows (via KVM-like USB switcher) and I'm generally pretty happy with it. A glitch here and there but nothing a power on/off doesn't fix. Have used it for a bit of music production hobby also, no problems.

I use it with a JDS Atom amp but that's probably overkill.

 

[iionas]

FWIW I have the MOTU M2 using with both Mac and Windows (via KVM-like USB switcher) and I'm generally pretty happy with it. A glitch here and there but nothing a power on/off doesn't fix. Have used it for a bit of music production hobby also, no problems.

I use it with a JDS Atom amp but that's probably overkill.

How is the difference without the amp? Ive produced forever without an amp however recently i plugged it into a friends amp and I thought i could hear everything more clearly.

By this what I mean is that I dont have to mix down and bounce out and reference to say 2-3 different devices in order to hear everything

 

[staticV3]

The way i understand the calculations is that these will be powered but wont be enough to saturate and actually get the full potential out of them.

No. Please don't understand anything below 200mW output as "not able to extract the full potential". That's a misconception. 111dB Peak, 96dB AVG is really loud. Probably much louder than what you listen to currently.
The full potential is long achieved by then.

200mW is what you need to break the headphone, not to get the full potential out of it.

 

[jae]

Get one of the Motu units, they have the least flaws. Even the M2/M4 is more than enough if you don't need digital out.

 

[iionas]

No. Please don't understand anything below 200mW output as "not able to extract the full potential". That's a misconception. 111dB Peak, 96dB AVG is really loud. Probably much louder than what you listen to currently.
The full potential is long achieved by then.

200mW is what you need to break the headphone, not to get the full potential out of it.

Cool that's what my thought was also, what I was trying to understand and k think you've done a great job of it is that it has enough power to give a good linnear output so that I don't have things changing on me.

I would honestly say 85 would be enough for the purposes I'm serving (listening to music during work, content consumption and production)

Does that make some sort of sense to you?

Hope it does

 

[iionas]

Get one of the Motu units, they have the least flaws. Even the M2/M4 is more than enough if you don't need digital out.

Mate it will be a Motu no matter what I'm just trying to decide if it's worth the coin to spent on the mk5. It has bit and pieces extra but most of it is fluff I don't need.

The DSP would be nice but end of the day it's not a need or a use case for me.

I've been trying to understand is there's actually huge differences between the sound reproduction in-between the M6/M4/M2 and say the mk5.

So far I have come up with nothing

 

[staticV3]

I've been trying to understand is there's actually huge differences between the sound reproduction in-between the M6/M4/M2 and say the mk5.

So far I have come up with nothing

The M2/4/6 all have identical headphone Amps, so no differences there. The mk5 has been measured by both Amir and Krause and has a more powerful Amp.

 

[iionas]

The M2/4/6 all have identical headphone Amps, so no differences there. The mk5 has been measured by both Amir and Krause

The M2/4/6 all have identical headphone Amps, so no differences there. The mk5 has been measured by both Amir and Krause and has a more powerful Amp.

Yeah as expected.

I think the better option here would be going with an M4/M6.

So from what I comprehend from you I think in the world world the Amps inside all of these units will reproduce sufficient sound volume and linnearly