[glc]

Quote:

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:

1. Distortion from the amp
2. Coloration from the amp
3. 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?

Lol, this is hilarious, you haven't heard the K701 through a EF5? yet you are telling everyone what I heard is distortion, coloration or placebo & then saying I am misleading? 
 

 

[Head Injury]

Quote:

Lol, this is hilarious, you haven't heard this through a EF5 yet you are telling everyone what I heard is  Distortion, coloration or placebo&  saying I am misleading? 

What else is it?

 

[Happy Camper]

Power and loudness are not the same. The 70x do step up with more power but it's the subtle things you notice. AKG says 150 mw but twice that with a strong power supply makes them sound pretty good. Using lesser amps and pushing them to their limits will sound worse. IMO

 

[Head Injury]

Quote:

Power and loudness are not the same. The 70x do step up with more power but it's the subtle things you notice. AKG says 150 mw but twice that with a strong power supply makes them sound pretty good. Using lesser amps and pushing them to their limits will sound worse. IMO

Actually power translates directly into volume. Volume is in dB, power is in mW. Most headphones have their sensitivity published as dB/mW. It's a direct relationship.
 
Note that the K701 in particular is published as dB/V, but since voltage is related to power too (P = I * V) they can be interchanged with some maths.

 

[Wapiti]

Quote:

Mine sound virtually the same unamped.

As this is the case, save yourself a bit of money and sell the amp.  All that matters is that you enjoy your music on your setup.  If the amp adds nothing, move on.
 
Your amp incorporates crossfeed, IIRC.  Do you use and enjoy this?

 

[menchi]

The main question really is: "I don't seem to notice changes in music listening with the AKG 702s amped or unamped? What is the problem here?"

The first question you need to ask is: "Is it me?"
Not everyone perceives differences in music the same, if at all. If you don't hear a difference in your music between an iPod Touch and a computer source that is semi-amped, then stop bothering yourself over it. You have found your limit and the happiness that is relative for you. Be happy that you have saved yourself out of a couple hundreds and continue to enjoy your music life.

I personally could not say the same for myself. I had many different headphones, and the K701s I owned sounded the worst out of all of them when used raw, despite the fact that I was comparing it to headphones that were more as well as less expensive than it.

The second question to ask is: "Is the equipment I have suited for the headphones I use?"
Just as no sane head-fier would solely use a uDAC or something of that level to power HD850s, one has to keep in mind the level of return one expects for the equipment they purchase. Why do you think there are so many threads with people obsessed about how or if X amp/DAC is best suited for Y headphone? Synergy is a big part of the equation, and just randomly slapping two different pieces of equipment and expecting them to pull their full potential is a foolish endeavor. And it just so happens, the K70x series are one of the most picky with which amps they are synergistic to.

 

[Head Injury]

Now if only someone could explain what synergy means. It apparently has no basis in known electronics. Though the K701 has low impedance, its impedance curve is fairly flat and won't be affected too much by output impedance. The Sennheiser HD595 and 598 (and probably 555/558 too), on the other hand, have a huge spike in their impedance curve at about 100 Hz, which is going to make their sound signature change much more with output impedance. But you never hear about them being picky.

 

[estreeter]

I've definitely made some mistakes in my short time in this hobby, but I'm very thankful that I have avoided these cans, in whatever color/marketing getup AKG see fit to adorn them. I'm not denying that there is potential locked in those drivers, but who needs something this temperamental ??

 

[Mochan]

Quote:

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.

I'm pretty sure you do listen loud, an iPod Nano 6G (less gain than iPhone) can push my K701 to listening levels - but it has to do it at about 90% of the digital volume meter. Problem is at this point the sound does start to clip and the mids get quite a bit harsh as a result. But they are able to put the sound to a good listening level for me -- and I don't listen loud. Now I tried it on my iPhone and had to put it to about 80% to get similar sound level. 
 
If this level is too soft for you... you definitely like to listen loud. Louder than I do, anyway.
 
Now if I plug it into the Mustang LOD to Nano I can keep the volume pot to around 10'o clock which is roughly 40% volume, and I don't get the same clipping distortion, so the mids are much smoother. Whew thank goodness.

 

[Nick01]

Quote:

Now if only someone could explain what synergy means. It apparently has no basis in known electronics. Though the K701 has low impedance, its impedance curve is fairly flat and won't be affected too much by output impedance. The Sennheiser HD595 and 598 (and probably 555/558 too), on the other hand, have a huge spike in their impedance curve at about 100 Hz, which is going to make their sound signature change much more with output impedance. But you never hear about them being picky.

Bright amp shouldn't be used with bright headphones.....RSA Predator with Grado GS1000i is a no no. Dacport with the GS1000i much better.
 

 

[Willakan]

Quote:

I've definitely made some mistakes in my short time in this hobby, but I'm very thankful that I have avoided these cans, in whatever color/marketing getup AKG see fit to adorn them. I'm not denying that there is potential locked in those drivers, but who needs something this temperamental ??

 
They really aren't very temperamental at all. They need slightly more power than the HD650s and an amp with a low output impedance. Everything else is just crap made up by a rabid fanbase at the time of release, who were unable to deal with the fact that some people did not like the sound of their favourite headphone and thought of increasingly irrational ways to explain such things rather than admitting that it was not perfect. The funny part is, half of them ended up driving them from tube amps to "add much needed warmth and coherence" (or something), which generally have much higher output impedances and doubtless made things much worse, especially for first-time buyers who were fooled into buying high-output impedance gear and then wondering what had happened to the bass(yay for under-damping!).
 
And this from a K702 owner.
 
@Nick01:
 
Or I could get a neutral (read: well-designed) amplifier and correct any perceived deficiencies in my headphones with an EQ?
 
 

 

[Digital-Pride]

Quote:

Now if only someone could explain what synergy means. It apparently has no basis in known electronics. Though the K701 has low impedance, its impedance curve is fairly flat and won't be affected too much by output impedance. The Sennheiser HD595 and 598 (and probably 555/558 too), on the other hand, have a huge spike in their impedance curve at about 100 Hz, which is going to make their sound signature change much more with output impedance. But you never hear about them being picky.

Head Injury, powerful headphone amps like Hifiman's EF-5 or Burson's HA-160, are not just about power output, but about the absolute control these amp exert over said headphone drivers that result in things like improved detail extraction, sound stage depth and imaging, bass extension and control and overall sound refinement.  It's headphone amps like these that enable the higher end headphones to really show what they're capable of.  Yes, the power output is a bit much compared to what is actually needed to comfortably drive them to a listening level, but the resulting sonic goodness is absolutely worth it.
 
Synergy is something I'm still learning about myself, though I would say there are headphone amps out that work well with almost any headphone out there.

 

[Digital-Pride]

Quote:

Quote:

I've definitely made some mistakes in my short time in this hobby, but I'm very thankful that I have avoided these cans, in whatever color/marketing getup AKG see fit to adorn them. I'm not denying that there is potential locked in those drivers, but who needs something this temperamental ??

 
They really aren't very temperamental at all. They need slightly more power than the HD650s and an amp with a low output impedance. Everything else is just crap made up by a rabid fanbase at the time of release, who were unable to deal with the fact that some people did not like the sound of their favourite headphone and thought of increasingly irrational ways to explain such things rather than admitting that it was not perfect. The funny part is, half of them ended up driving them from tube amps to "add much needed warmth and coherence" (or something), which generally have much higher output impedances and doubtless made things much worse, especially for first-time buyers who were fooled into buying high-output impedance gear and then wondering what had happened to the bass(yay for under-damping!).
 
And this from a K702 owner.
 
@Nick01:
 
Or I could get a neutral (read: well-designed) amplifier and correct any perceived deficiencies in my headphones with an EQ?
 
 

Or you go for the Q701.

  You know want the green outfitted master.

 

[Willakan]

What exact "control" do such expensive amplifiers exert above others?

 

[mikeaj]

Quote:

What exact "control" do such expensive amplifiers exert above others?

Wallet control. 

 
Possibly more damping factor and less ringing from borderline oscillation, less distortion / no clipping if cranking up the volume?  This is if "expensive" is taken to mean "better" in the traditional high-fidelity sense.  It's hard to guess what other people hear.