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Akg K-702 - Amped vs Unamped : Can't hear much of a difference?

post #1 of 86
Thread Starter 


Have you AB'd material with your hard to drive headphones when 'unamped' vs 'amped'? I have, multiple times.


For your info my signal chain is as follows : M-Audio ProFire 610 => Meier Audio Corda Arietta => Akg K-702


After switching the Arietta in/out of my signal chain, I have only noticed a slight warmth being added in the lower-mids with the Arietta. Whether this is a good or bad thing depends on my mood, and what I am listening to.


What IS bad though, is that there is such a small difference between my unamped and amped headphone.


Now when I first bought the amp, I of course thought it improved my sound etc. Well, talk about placebo.

I have now had it for a few months, and decided to AB once more. After several days of this I have concluded it may not be worth the $ I thought it was.

Searching this up on the internet seems to contradict my thoughts, eg. "You really need an amp to realize its potential etc." <= What does this statement even really mean? What is this 'potential' everyone speaks of? Mine sound virtually the same unamped.


What have you guys heard, personally, after AB tests on multiple material?



Edited by senjy - 10/30/11 at 12:02am
post #2 of 86

The ProFire isn't necessarily "unamped". I don't know how powerful it is, but I expect it has low distortion.


Headphone "potential" is a mystery to me as well. As long as you have enough volume without clipping, low noise and distortion, and low output impedance, I would think a different amp won't help much. No one's yet fully explained to me what's magic about obscene amounts of power, or this opamp versus that opamp when the end result is statistically inaudible.


I've very, very briefly done a sighted AB test between the Benchmark DAC1 and my soundcard with the LCD-2. I heard nothing, so the DAC1 was packed up within the hour. It's technically superior in every way, but the differences are beyond audible at that point. I wouldn't necessarily trust my impressions, as by then I was convinced I'd keep the card instead, but at least the numbers back them up. There is still the flaw of high output impedance with the soundcard that I'll correct with an Objective2 in the future, only as a project and not out of necessity or expectation of sound improvement.


When I first got my uDAC, I didn't hear a difference between it and my old X-Fi XtremeGamer card, though I convinced myself over the course of the day that it was worth the money. In hindsight, there probably are audible differences between the two. The uDAC is worse!


These critical posts warm my heart, they really do.


As a point of clarification, do you get that extra warmth with or without the amp? It sounds like the result of output impedance, but the Arietta's is supposed to be very low.

Edited by Head Injury - 10/29/11 at 10:30pm
post #3 of 86
Thread Starter 

You're right, no the ProFire isn't "unamped", but it's 'technically' not rated to be able to drive the K702's properly. So says everyone.


Why not? I can take the levels so high as to damage your ears, and more, even though it supposedly is not right for it.


The Arietta, however, is supposedly suitable...


Also, I don't want an amp to 'colour' my sound, so that leaves it the mysterious 'potential' and also getting it loud enough, which my 'unsuitable' Profire 610 can.


I own the uDac as well, its gathering dust but it was an upgrade to my onboard soundcard :D


Edit: I've edited my original post to state that it is with the Arietta that the low-mids get a broad boost (others have also made this statement, it is a part of the amp's 'colour', not a problem with output impedance as it is very low). Also let me reiterate that sometimes I like it , sometimes I don't. Can't hear it doing anything else to my sound, so where's the fulfilled 'potential' everyone and their moms harp on about?





Edited by senjy - 10/30/11 at 1:43am
post #4 of 86

Well...have you tried the K702 plugged directly into a laptop? I have and it's bleh

post #5 of 86
Thread Starter 

Probably does blow from a laptop (or so i've been led to believe, read on), but my interface has a built-in headphone amp - although apparently its not suitable for these 'hard-to-drive' k702 headphones.


I also have AB'd from my ipod touch and then from my ipod touch into the Arietta into the k702. Same no difference. What goes?

There's a difference between my ipod and my interface, that's for sure, but headphone amp makes no difference.


Anyone else who has done AB testing? At this point I'd probably like to hear from those who's headphone amps cost more than their actual headphones.



Edited by senjy - 10/30/11 at 12:47am
post #6 of 86
Thread Starter 

Here's more clarification of my AB testing done with an ipod touch.


Contrary to popular belief, my own listening has shown that there is no


  • Tightening or boosting of bass
  • Taming of highs
  • Widening or opening of soundstage


Any other changes in your sound going from badly amped to properly amped will be colouration, harmonic distortion etc. from your new amp, or worst of all, a placebo effect from a combination of both your expectations or incorrect level matching (even if you get it to the exact same level during the AB test there will always be those precious moments of twiddling the volume which mess with your perception)


This is only my listening on my systems, this is your time to talk about yours.




Edited by senjy - 10/30/11 at 12:58am
post #7 of 86

Well my K702 cost $200 and my RSA Predator is $500. ABing before and after amping is night and day.

And my iphone def couldn't pull the K702  to anywhere near my normal listening level, and I don't listen loud.

post #8 of 86
Thread Starter 

I just retried my vol control on my itouch because of you Nick.

When I hit around 80% I went "ah ****" and had to pull back before I permanently damaged my ears. If I listen normally like this Ipod Touch => K702 I have the volume at 25%. 80% was past my threshold and painful as if my friend had played a trick on me with the volume (xD). Have you been listening for many years (have you been alive for long? :P)?


Your comment about the RSA Predator is interesting, however your AB testing is useless unless you have been using the same DAC. As I understand it the Predator is a combination DAC/Amp, so what have you been ABing with? It is most likely the DAC that is making the 'night/day' difference.


If not, is it only the loudness level that is different? (as your iphone comment tells me you have hearing damage, and quite severe at that unless the itouch and iphone construct their headphone outs extremely differently. If I am wrong forgive me tongue.gif)





Edited by senjy - 10/30/11 at 1:37am
post #9 of 86

Dang it!!! I don't have a K702 to try on atm. Sold it lol  biggrin.gif

post #10 of 86

Okay...I pulled out my AKG K242 and the Just Audio AHA120 (this is just an amp, no dac). Clarity is something that I immediately noticed after ABing before and after amping. No amp, it sounds muddy and congested.


I'm not an audiophile at all. Just my $0.02

post #11 of 86
Originally Posted by Nick01 View Post

Well...have you tried the K702 plugged directly into a laptop? I have and it's bleh

depends on the laptop really. i forgot what model it was but it was an older Toshiba laptop my friend has and i use it when i'm babysitting since it's really early in the morning and i usually get there while the kid is still asleep but i use to use my 240DF straight off the headphone jack and for playback it was more impressive then i thought it would of been and seem to have enough power at max to get my 600ohm DF's at more then enough audible gain while maintaining it's precise clarity.
post #12 of 86
I owned a k701 and will tell you that there was a noticeable difference in sound quality for me listening through a laptop versus listening through one of my more powerful portable amps (Pico, SR71A, Predator). the big difference does not show up until you start sending the signal through a desktop amp. For me, the moment i discovered what the k701 was capable of came when I ran the signal through a HiFiMan EF5 hybrid that came with my HE5. I sold the K701 though because the HE5 was the getting all the listening time.
post #13 of 86
Originally Posted by glc View Post

For me, the moment i discovered what the k701 was capable of came when I ran the signal through a HiFiMan EF5 hybrid that came with my HE5.

The EF5 has a maximum output of around 15Vrms. That's over five times more voltage than the K701 needs to reach 110dB, which is really loud already. That means the EF5 is capable of driving the K701 to around 125dB, maybe more depending on that particular K701. That's enough to damage your hearing permanently within a minute.


So why do you need it that loud? What benefit does it bring you? What benefit does it bring you when you don't even use that volume, when you keep the knob turned way down? The other amps you've tried are perfectly fine. Low distortion, plenty of power (exception there being the Pico, maybe).


The "potential" you discovered was more likely that not:

  • Distortion from the amp
  • Coloration from the amp
  • Placebo


It's great that you like it, but why continue the misleading trend that others need so much power? Why mislead with something like "the big difference does not show up until you start sending the signal through a desktop amp"? Why does it matter if it's a desktop amp or a portable amp? Because one's bigger and shinier and looks more impressive?

post #14 of 86

It's 'cause people like shiny things and expect there to be a big difference, whether they (1) spent a lot of money or (2) built it themselves.


With some headphones, there can be a big difference; for example, a multi-balanced armature IEM (with crossover) is not going to play nice at all with the ProFire 610's supposed output impedance of 75 ohms.  K701 has relatively flat impedance over 20 Hz - 5 kHz and just goes up some to 20 kHz, so there shouldn't be much less interaction there.  Also, with some amps there definitely can be big differences, if they're designed to sound different, by rolling off some frequencies, adding euphonic (or not) distortions, and so on.


Also there tends to be a lot of group think on forums such as these.  K701 / K702 / Q701 is relatively insensitive for the impedance, so it requires more current than some other headphones, which means it's not a good match with some amps.  Thus a reputation develops.


All three amps you're listening to are probably relatively neutral, so that's that.  Possibly you don't listen as loud as other people, and louder volumes would put more of a stress on the amps and would make you never consider the iPod for volume concerns, etc.  Maybe you will find more of the headphone's "potential" by listening to different music.

post #15 of 86

Just looked at the specs of your interface. Two specs stood out:


1) Output into 32 ohms: 60mw. It isn't hugely impressive, but it demonstrates the amplifier has a reasonable amount of power (bearing in mind a Clip+ puts out about 20mw). If you listen at reasonable volumes, this would probably be fine.


The guy above has already addressed the output impedance.

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