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EMU-0404 USB as Amplifier for AKG K-701?

post #1 of 14
Thread Starter 

Hello Everyone,


(my very first post so I hope it's not in the wrong forum)


I'm planning to buy an AKG K-701.

Right now I have a Sennheiser HD-595 driven by an external soundcard the EMU-0404 USB.

It has the AK4396 DAC.


Does anyone have any experience regarding how sufficing is something like EMU-0404 and it's DAC for driving the K-701?


If you think that EMU-0404 isn't enough and I should get an amp please tell me what do you recommend, and why are those certain amps better, and in what aspects than my EMU-0404.


EDIT: Maybe I should have asked if the actual headphone output and it's amplifier on EMU-0404 is sufficient for K-701 not only the DAC.

And when I mean sufficient I'm not only talking about volume level but SOUND itself.


Edited by freeborn - 11/8/10 at 2:25pm
post #2 of 14

Hi, I never tried the combo but had 0404 usb and it can power HD600 sufficiently but not optimally. Since you already have the emu why not get the AKGs and see for yourself?

post #3 of 14

I have this combo. I can tell you the EMU 0404 USB does not have sufficient power to drive it to its full potential. I went to canjam and was able to listen to a properly driven K701 out of an amp. When I got the EMU 0404 USB, it sounded very different; Less detail and weak muddy bass. You will hear a huge improvement going from EMU 0404 USB to a dedicated amp. I was worried the K701 might be bass-light so I plan on building an M^3 amp w/ bass boost.


What is your source? (Laptop, iPod, etc.) I bought the EMU 0404 USB solely for DAC and ADC since I do both listening and recording. If you're not planning on recording, you only need a DAC. What medium are you going to connect your source and DAC? fiber-optic, coax, usb, or firewire?

post #4 of 14
Thread Starter 


Thx for the answers!


My primary source is gonna be PC and mp3 files, but I might as well use it with an ipod nano.


I'm using the EMU for recording as well  with a perception 200 (AKG).


I'm pretty much limited in the choice regarding the medium of connecting the DAC to the source since the EMU is USB.


But if you have a better solution for me (DAC + amp) then I have firewire, and USB on my pc.

Furthermore if we need SPDIF or optical the EMU can provide these.


Anyways after reading your post I'm pretty sure I will get a dedicated amp, so if anyone could link me some threads on this topic I'd be really grateful.


EDIT: Just talked to the guy selling the K-701 and he told me he's already sold it but he has another can which also has the capsules of a K-701 but in the Bodyof a K-500 which makes the sound more open. I made a separate post about that

I know it's pretty offtopic but what do you think about buying such a headphone for 238$? I think AKG had a reason to put K-701 capsules into the body where they are, and I'm affraid the K-500 might make it sound "too open" or something like that.

If you want to answer on this OT please do it here: http://www.head-fi.org/forum/thread/522025/k-701-capsules-in-k-500-case

Edited by freeborn - 11/9/10 at 9:07am
post #5 of 14

You can always keep your EMU as a DAC and add a dedicated amp to it.


The 0404 uses 1/4" balanced jacks for output though, so you'd need to get or mod a cable to connect it to an RCA-based source (assuming the amp will have RCA inputs).

post #6 of 14
Thread Starter 

Hey MadCow,


I am going to ask a partly hypothetical question here, but it has it's real aspect as well.

Tho I have learned DSP @ university I have never asked anybody about the following:


Does such a DAC system exist where the digital source, the quantized samples is transformed to analog in such a manner that it has such a volume level so that's sufficient to drive the target device such as a headphone in this case, without requiring further amplification. 


The reason why I'm asking this is because if there is such an amp for headphones than the perfect way of feeding that amp is providing quantized samples, digital data. This way there is a minimal amount of "boxes" in the queue.


If you look at the whole system from the samples to the membrane of the cans then you must say the best way of transformation must be the simplest one, one "box" but that one is the closest to perfection, reason being if you consider signals in the frequency domain then you know that each amplification including the DAC where the nascent analog signal is born can be regarded as a "box" with its own transfer function, and the result is the product of those transfer functions. The more "boxes" we include the more errors or distortions will be present.


So let's say the analog jack output of my EMU-0404 has transfer function EMU_DAC(s),

while the desired above described ideal headphone amp has transfer function DESIRED_DAC(s).

The result analog signal that we send to the cable of the headphone is R(s)


If such a system existed where the DAC "directly" drives the headphone then its amp would be the only "box" in the queue, so it would look like R(s) =DESIRED_DAC(s)


Tell me if I'm wrong and no such system exists, because every headphone amp if it has digital input has its own inbuilt AMP_DAC creating a weak analog signal SEPARATED from its inbuilt END_AMP therefore in reality it looks like this:


EDIT: I meant separated by being a separate entities which are of course connected.


R(s)=AMP_DAC(s) * END_AMP(s) 


So in conclusion that's why MadCow tells me "You can use the DAC of EMU" cuz in that case it will be:



If this is the case (no ideal can amp exists) then is the AK4396 DAC of EMU-0404 directly feeding the rear jack output on my EMU-0404?

So no other further amplification "box" is in the queue?

Is it like R(s)=EMU_DAC(s) or R(s)=EMU_DAC(s)*BALANCED_JACK_OUTPUT_AMP(s) ?


Because if there is further amplification  on the 1/4 jacks then it's just makes no sense to use it, then I'm better of using a dedicated amp that can receive digital inputs and has its own HQ DAC and end-amplifier.

Edited by freeborn - 11/9/10 at 7:14am
post #7 of 14

Hi freeborn,


If I *think* I understand what you're describing -- theoretically such a thing is possible, but I am not aware of anyone making such a device.

The closest product that I can think of is the Wadia PowerDAC -- it has a digital volume control that attenuates the digital signal, the DAC feeds the power amp directly (rather than generating a line-level signal that then goes through a preamp or attenuator and amp section). However, the PowerDAC is meant to drive speakers; I haven't heard of any similar product specifically for headphones.

post #8 of 14

I have a E-MU 0404 USB and it is not powerful enough to power the K702 that I have to full volume. Also, the headphone jack's output impedance is about 22Ohm I believe.


These days, I have a E9 connected to the line-out of the 0404 USB and it provides more than enough power to drive the K702's. This is a great combination as the 0404 USB is a very good DAC in terms of raw audio performance. 


With respect to why there would need to be a an amp, the simple answer is that DAC chips do not provide nearly enough output to drive high impedance and/or low efficiency headphones. So there has to be an amp somewhere. In the interest of keeping costs low, DACs therefore are built to provide a high quality line level output which can then be amplified by an amplifier. Some DACs have a built-in headphone amplifier circuit that's separate from their line-out circuit, but most of those are not powerful enough to drive high impedance and/or low efficiency headphones either. 



post #9 of 14

0404 usb does have headphone amplification Jack or have I misunderstood you?

post #10 of 14

Yes it does have headphone amplification, but the available power output is not sufficient for high impedance/low-efficiency headphones, a category that the K70x headphones fall under. 


It was usable, but having an outboard amp like the E9 made it a lot better.  To put it another way, the 0404 USB is well regarded as a DAC, but its headphone output is not one of its strengths.



post #11 of 14
Thread Starter 

I'm very grateful for all the info provided so far!

Thank you everybody!

post #12 of 14

Would EMU 0404 USB with its 22ohm output impedance and maximum output power of 20mW be able to drive Beyerdynamic DT880 250ohm?

post #13 of 14
Originally Posted by 66z View Post

Would EMU 0404 USB with its 22ohm output impedance and maximum output power of 20mW be able to drive Beyerdynamic DT880 250ohm?



The 0404USB does not drive the Beyers to their full potential.

post #14 of 14

Is there any DAC/audio interface that does?

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