[soldier9599]

I'm well on my way to getting AKG K702's and I've been thinking about pairing it with the E7/E9. EDIT: OK, never mind, I seem to have found the answer to my question. When used with a PC the sound will go through USB, bypassing the sound card to be processed by the E7/E9 instead, am I right?
 
Also, I'm still not set on the E7/E9, but I was under the impression it was the best bang for your buck. Anything more expensive is out of the question for me. Is there anything as good or better for a similar price?

 

[skamp]

The E9 wouldn't suit the AKG K702s (62 ohm impedance) because of the E9's relatively high output impedance (10 ohms for the 1/4" jack and a whopping 43 ohms on the 1/8" jack). The E7, with its near 0 ohm output impedance, is a match, however.

The E9 is not only unnecessary, it would be detrimental to your headphones. Just get the E7 and save your money.

 

[soldier9599]

Is the amp in the E7 going to do the job on it's own? I see how the impedance could be an issue for frequency response, but I was under the impression adding the E9 made a noticeable improvement because it supplies the juice the E7 can't. Won't a low power amp paired with high impedance headphones give you more frequency response deviation than slightly high output impedance? With a ratio of 1/6 being as close as it is to 1/8, I feel like I would expect a variation of only around 1dB which is borderline audible, which is a sacrifice I might make to save a couple hundred bucks. I know I'm just a noob here spewing out confused babbling, but I'm still not convinced the E7 will do the trick on its own, nor is the writer of that article. Is there any DAC/AMP combo you could think of within the $200 range that otherwise performs as well as these two that might have an output impedance of under 8 ohms?

 

[skamp]

The E7 has more than enough juice for such headphones, and I believe NwAvGuy pretty much says so. Yes the E9 has more juice, but it simply won't be used. It's more tailored for 300 ohm / low efficiency headphones…

 

[Captain Magenta]

Ok, I'm no expert on this matter but I have the E7/9 and have used them with quite a few headphones.  I was using my K240S with just the E7 and was reaching 50 out of 60 on the volume level at times.  Tried it with the E9 and there is a big improvement.  I recently got the K601 which is 120 ohm and meant to be harder to drive than the 702 and I've not even bothered to try it with the E7.  On high gain I don't need to go past 11 o'clock.  I would strongly suggest you get the E9 and I believe the vast majority on here would agree that the E7 is not enough.  You don't want to be maxing out an amp.

 

[skamp]

OK, I think I misread the sensitivity rating. It reads 91 dB/mW, 104 dB/V for the K240S, which is fairly low. My bad.
If you get the E9, make sure to use the 1/4" jack.

 

[soldier9599]

Thanks guys I appreciate the input.

 Still leaning towards E7/E9 but I'm gonna keep looking. Anyone have any other ideas in the same price range? Everything good seems to be out of my price range.

 

[Captain Magenta]

Quote:

Thanks guys I appreciate the input. Of course we're just talking about the opinion of one person, but for what it's worth the writer of that article did post "...

if the E7 has enough output for your low impedance headphones (it doesn't with some, like the AKG K701 for example)." At this point I'm still leaning towards getting both E7/E9 unless I can do better for the same price which isn't looking promising so far.

.
I've pondered this question for some time and not come up with anything better as of yet without spending significantly more.  The general consensus seems to be that the E7/9 seems to be great bang for buck.  Sure there are plenty of doubters but there are so many people each with their own opinions.  What I can say is that the E9 was supposedly not powerful enough for the K601 but as I said above I don't need to go past 11 o'clock with high gain.  Even with low gain i'm never past 12.30.  That goes with my vintage 600 ohm K141 too.  Sure there are amps of higher quality and people talk about voltage swing which I don't understand the in-and-outs of yet but I'm satisfied with the E9 at the moment and my wallet strongly agrees.

 

[soldier9599]

What about E10/E9 instead of E7/E9? Should I expect more out of the E10 than the E7? I have Audio-Technicas I lug around everywhere so portability really isn't a major concern.

 

[skamp]

What about E10/E9 instead of E7/E9? Should I expect more out of the E10 than the E7?

Despite some issues, NwAvGuy says the E10 is an upgrade to the E7. I don't know if the E10 would provide enough power on its own for your headphones, though.

BTW, I figured out the formula for converting headphone sensitivity expressed in dB/V into dB/mW:
dBV - (10 * log(1000 / Z))
Z being the headphone impedance.

For your AKG K702s (105 dB/V, 62 ohms) that translates into 93 dB/mW, compared to, say, my Denon AH-D2000s (106 dB/mW, 25 ohms). Your AKGs require quite a bit more juice than my Denons indeed. How that translates into amplifier specs, I don't know.

Edit: NwAvGuy's chart states that in order to achieve a sound pressure level of, say, 110 dB, your AKGs require ~50 mW, compared to my Denons which require only 2.5 mW).

Edit 2: corrected figures

 

[stv014]

Quote:

What about E10/E9 instead of E7/E9? Should I expect more out of the E10 than the E7? I have Audio-Technicas I lug around everywhere so portability really isn't a major concern.

The E10 can output more power than the E7, and is more likely to be sufficient on its own without the E9. Alternatively, you may also get the O2 instead of the E9.
 

 

[stv014]

Quote:

Won't a low power amp paired with high impedance headphones give you more frequency response deviation than slightly high output impedance?

Power does not affect frequency response (well, except maybe perceptually due to the lower volume), only distortion if you try to exceed the maximum. High impedance headphones are actually less prone to frequency response variations from different sources than low impedance ones.
However, the E7 may indeed be lacking in power unless you listen at low volume and/or to music with limited dynamic range.
 

 

[9VARZ]

Hmm....
 
I personally think the Arcam rPAC deserves a lot more attention.
 
I've done a mini review of it here. Do check it out!
 
It is around the same money as the E7+E9 combo (only a marginal top up there). But IMO, it does a MUCH MUCH better job than the FiiO combo. Good VFM!