[tdockweiler]

Everyone should get an amp when buying the K702. The Total Bithead previously mentioned cant drive the K701/K702 well. It's basically a $99 Airhead with a DAC built in. It's mostly a portable amp. It can drive the HD-650 quite well, but had trouble with my K701.
 
The E9 is a great starter amp for the K702, but it doesn't make the K702 sing. I upgraded to the Headroom Micro amp and it really makes them sound so good! For $350 it's quite powerful and even more powerful than my E9 and Asgard. It's half the size of the E9 too and is built like a tank!
 
E9 will be fine, but a better amp with good synergy will take it to a whole new level I think. I also heard the Matrix M-stage is quite good for them.

 

[Solomyr]

What I am trying to understand is what difference a headphone amp will make to the sound - I don't need it to go any louder, but if it significantly improves the sound quality then I am all for it. I don't know what you mean "sing". Can you elaborate?
 
I am considering the Fiio E7 as I would need a portable amp, but if anyone cam recommend a different portable one in a simialr price range it would be appreciated.
 
Quote:

Everyone should get an amp when buying the K702. The Total Bithead previously mentioned cant drive the K701/K702 well. It's basically a $99 Airhead with a DAC built in. It's mostly a portable amp. It can drive the HD-650 quite well, but had trouble with my K701.
 
The E9 is a great starter amp for the K702, but it doesn't make the K702 sing. I upgraded to the Headroom Micro amp and it really makes them sound so good! For $350 it's quite powerful and even more powerful than my E9 and Asgard. It's half the size of the E9 too and is built like a tank!
 
E9 will be fine, but a better amp with good synergy will take it to a whole new level I think. I also heard the Matrix M-stage is quite good for them.

 

 

[tdockweiler]

Each and every headphone amp "usually" will make a headphone sound different. Many people think this is not true, but I think it is. There differences can be so minor or there can be so much of a change to make you go from liking a headphone to loving it. Some amps pair up better with some headphones than others. It's important to find an amp that has good synergy with a headphone. I do think that many headphones will work equally as good on any amp. For example, I can't tell a huge difference between my HD-598 on three different amps. I actually didn't love the K702 until I tried the E9! Totally transformed them compared to the Asgard. Some headphones are really picky about amps. My K702 and HD-650 are like. They sound different on all of my amps and not just subtle differences.
 
For example, my K601 was pretty terrible with my Schiit Asgard. That headphone loves the HD-600, but not the K601. It also didn't make the K702 sound that good and made the mids sound recessed. Once I switched to the E9 that has better synergy, the K702 was much better. The Asgard is a good amp, but a better match for some of the Sennheiser headphones it seems like. To make matters worse, I prefer my HD-650 on the E9 more so than the Asgard somtimes. Mostly because the E9 is more neutral and a tad more clear (to my ears). The Asgard does make it a bit more fun to listen to. HD-600 was better on the Asgard compared to the E9 though.
 
Despite my like of the E9, the K702 on it didn't quite "WOW" me. I guess what I mean is that the K702 really comes alive on a better amp like the Micro Amp or maybe the Matrix M-Stage. The mids sound fuller and everything sounds not so distant anymore. Perhaps it's coloring the K702 a tad, but I like it! So far the K702 on the Micro Amp is the best I've heard it and I don't even want to know what it sounds like on a $1000 amp!
 
It varies on headphones, but most amps will most definitely improve the sound of a headphone. If it's an easy to drive headphone, then probably less of a chance.
 
I personally don't think many portable amps can drive the K702 very well, at least not to 100%. Many that can probably cost $200+. I think the K702 sounds decent un-amped, but they really need a desktop amp. I don't think the E7 can drive the K702 well. The E9 is a good place to start, but a better one is always suggested. I think most people should find the E9 and K702 quite good. I think the K702 is deserving of a more expensive amp though.
 
 
Quote:

What I am trying to understand is what difference a headphone amp will make to the sound - I don't need it to go any louder, but if it significantly improves the sound quality then I am all for it. I don't know what you mean "sing". Can you elaborate?
 
I am considering the Fiio E7 as I would need a portable amp, but if anyone cam recommend a different portable one in a simialr price range it would be appreciated.
 


 

 

 

[mikeaj]

A headphone amplifier is basically a device that takes an analog input signal (input voltage) and replicates it on the output (as a voltage level).  That voltage level is applied across your headphones, and it makes sounds.  Why not take the original input signal and use that directly to drive the headphones?  Headphones have fairly low impedance, so they require a decent amount of current (and more for higher volumes).  No real-world device is going to be able to sustain its output accurately while driving a load that's demanding a decent amount of current.  An amplifier is a device that's supposed to do that well under those kinds of conditions.
 
The implementation determines how different the output of the amp will be compared to the input, with different headphones, at different volumes, with different kinds of input signals (music), etc.  Some bad amps will have an output that is severely degraded compared to the input, so you notice things in the sound that aren't supposed to be there.  It could sound noiselike or something else.  There are many ways to measure and compare how the outputs of devices may be different.
 
If your current setup with the cans plays music loud enough for you, you're just looking at sound quality improvements.  One benefit of amps is that they allow you to crank up the volume more so we're going to ignore that aspect for now.
 
A lot of audiophile amps and products aren't really that accurate in reproducing the input signal.  Sometimes this is by design.  For example, you can add things to the sound or that weren't present (more harmonics for example) or tweak the frequency response, and that may make the music sound better to somebody.  Sometimes the designers just overlooked something and made a mistake.
 
You get different inaccuracies with different loads (different headphones).  So some combinations of headphones and amps may just not sound good together, hence "synergy" or the lack of it.
 
If the goal of two different amplifiers is to sound transparent (not sound like anything, as in reproduce the input as faithfully as possible aka high-fidelity), and they do fairly good jobs, there will be negligible difference between the two.  i.e. you would not be able to tell the difference between them with your eyes closed.  Partially because many people are looking for tweaks for their sound and also so different audiophile manufacturers can distinguish themselves, there is usually some incentive not to make audiophile gear be transparent.  If you're just interested in having the music pass through your system as clean as possible, there's certainly a point of diminishing returns on how good an amplifier you need.
 
 
edit: taking some numbers from the FiiO E7 review there (it should do about 50 mW into 62 ohms) and the AKG K701 spec of a nominal impedance of 62 ohms and a nominal sensitivity of 105 dB / V, some back-of-the-envelope calculations, the FiiO E7 should be enough unless you want to listen at peaks of close to 110 dB (pretty loud).  Maybe it won't do that much at frequencies other than 1 kHz with those headphones, since the bass is a little rolled off.  But that gives a rough idea of what to expect.  Other devices may do a better job (slightly) or produce a somewhat different sound, but for the price, it should do pretty well.

 

[Solomyr]

A lot of information there to digest.
Having had a look at the specs of the E7 vs the E5 they seem to be the same, but the E7 comes with a DAC. Will this get rid of the audible noise I get when the headphones are connected to my PC (regardless of whether music is playing or not)?
Also would i be better with the E5 when using my Cowon S9, or wull the E7 work fine with it too?
I live in the UK and we don't appear to have the same range of amps available as you do in the US.
 

 

[mikeaj]

Well, the actual performance of the E7 (as an amp only) and E5 is not the same.  The E7 is better in some ways and about the same in others, but it's not a huge difference.  Since the amp performance of the E7 is better than the E5, it would be slightly better for using with the Cowon S9.  If you're looking for a portable amp, there are other options though, even if you live in the UK.  The E7 also has more bass boost options and is larger, as you could probably figure out without me telling you. 

 
If there is significant noise coming into an amp, there will be significant noise coming out of the amp as well.  So apparently your PC's integrated audio is so bad that you have audible noise even on relatively insensitive headphones like the K701?  This doesn't inspire confidence about the integrated audio's DAC or amp.  Do you notice differences in sound quality between the PC and the Cowon S9, which I assume would be better?  People talk about sources being noisy when they hear noise on some IEMs that are like 110 dB / mW sensitivity at 16 ohms, which is way louder than the K701.  To hear noise with fullsize cans like that is pretty extreme unless you live in an anechoic chamber.
 
edit: if you're looking for huge sound quality improvements and you don't currently notice big differences between the PC and Cowon S9 aside from the noise, there is likely not huge improvements for you to find with any amp, at your current listening levels.  Don't expect miracles.  Well, maybe there's nothing wrong with your PC sound output other than the noise, but I wouldn't count on it.
 
Anyway, as I think you picked up, you could use an external DAC for your computer that would provide an audio output with less noise, to the point of it being inaudible.  An E7 is such a device.  An E5 and other amps are not.
 
Disclaimer:  many forumers and audiophiles will probably disagree about the E7 for a K701.  But if the volume of a portable player is enough, the E7 will be enough too.  As for driving it "well," it should also be enough, despite discussions on "singing" or "synergy" or "authority" or "power" (as opposed to actual power required, which we've gone through).  After all, head-fi has a subforum mostly dedicated to placebo effects.  No offense, just my opinion, based on the actual evidence.  Like I said, other devices can do the job more accurately, but they tend to be more expensive.  Others will do worse, even some that are more expensive.

 

[Solomyr]

The audible noise on the pc isn't anywhere as bad with the K702s as it is with my IEMs (UE700s), but it is still noticable. I do notice a difference between the pc and the S9, with the S9 being better. But I think I also need to re-rip my CDs into a lossless format as I notice a difference between listening to the CD and the mp3 rip on my pc.
My concern regarding using the E7 with the S9, as I had read in another thread, is that connecting the E7 to the headphone jack will cause the amps in the S9 and E7 to compete (or something like that), as there isn't a dock connector on the S9 just the jack and a USB connector.

 

[mikeaj]

Depending on the encoder and bitrate used for the mp3 rip and assuming that the data on the CD was actually extracted cleanly, the difference between the CD and mp3 may be negligible.  On most tracks it's impossible for humans to distinguish between the CD and modern 320 kbps mp3 or the CD and LAME -V0 mp3, by listening, even on high-end gear.  In many/most cases, LAME -V2 does a pretty transparent job as well.  If you've already ripped the CDs accurately with a sufficiently high bitrate, I would not bother spending time re-ripping unless you test yourself using something like foobar ABX and can actually tell the difference. 
 
Yes, it's suboptimal to run the (amplified) output of one device like the S9 into another amp.  Essentially you're using the first device's integrated amp to power the input of another amp.  Generally the input impedance of most amplifiers is pretty high, so it's pretty easy to send signals to them accurately.  You may have a problem, depending on how the S9 and the amp are implemented, but this can happen with the S9 and any amp out there.  I would guess that if the E7 presents a problem with the S9, the E5 wouldn't be any better.  Most amps probably wouldn't do any better in terms of the interaction with the S9's internal amp.  Anyway, "compete" is not the correct word to describe what's going on, in my opinion.
 
But it's also very possible that running through the extra amp will have negligible effects, and you'd effectively be using the superior amp for the output without significant ill effects.  I suspect that you won't hear too much difference between going straight out of the S9 and using a more neutral external amp, but it's worth a try.  Maybe there will be a good difference.

 

[tangelo]

+2 on K702 with the Maverick D1
 
Just be sure to change the opamps (a common setup is LT1364 for the DAC and LM4562 for the amp) otherwise it will sound (too) bright.

 

[Chokalait]

Mikeaj, this is a little late but your information helped out tremendously. There's just one thing I need to clear up before I make a purchase: Firstly, you suggested that the E7 would be sufficient for the K702s but I was thinking about using the E9. Since you can use the E9 as a standalone amp, what's the benefit of using the E7 over the E9? Would you need an E7 just so you could use it with laptops? It seems like in every way, the E9 is a better option, but in terms of cost, what's the incentive to buy both the E7 and E9 combo?
 
Quote:

Well, the actual performance of the E7 (as an amp only) and E5 is not the same.  The E7 is better in some ways and about the same in others, but it's not a huge difference.  Since the amp performance of the E7 is better than the E5, it would be slightly better for using with the Cowon S9.  If you're looking for a portable amp, there are other options though, even if you live in the UK.  The E7 also has more bass boost options and is larger, as you could probably figure out without me telling you. 

 
If there is significant noise coming into an amp, there will be significant noise coming out of the amp as well.  So apparently your PC's integrated audio is so bad that you have audible noise even on relatively insensitive headphones like the K701?  This doesn't inspire confidence about the integrated audio's DAC or amp.  Do you notice differences in sound quality between the PC and the Cowon S9, which I assume would be better?  People talk about sources being noisy when they hear noise on some IEMs that are like 110 dB / mW sensitivity at 16 ohms, which is way louder than the K701.  To hear noise with fullsize cans like that is pretty extreme unless you live in an anechoic chamber.
 
edit: if you're looking for huge sound quality improvements and you don't currently notice big differences between the PC and Cowon S9 aside from the noise, there is likely not huge improvements for you to find with any amp, at your current listening levels.  Don't expect miracles.  Well, maybe there's nothing wrong with your PC sound output other than the noise, but I wouldn't count on it.
 
Anyway, as I think you picked up, you could use an external DAC for your computer that would provide an audio output with less noise, to the point of it being inaudible.  An E7 is such a device.  An E5 and other amps are not.
 
Disclaimer:  many forumers and audiophiles will probably disagree about the E7 for a K701.  But if the volume of a portable player is enough, the E7 will be enough too.  As for driving it "well," it should also be enough, despite discussions on "singing" or "synergy" or "authority" or "power" (as opposed to actual power required, which we've gone through).  After all, head-fi has a subforum mostly dedicated to placebo effects.  No offense, just my opinion, based on the actual evidence.  Like I said, other devices can do the job more accurately, but they tend to be more expensive.  Others will do worse, even some that are more expensive.

 

 

[Ampeezy]

The Fiio E9 with the K702 is really nice