Originally Posted by Kodhifi
So my E7 came in today. I excitedly connected it with the ipod dock cable to my Iphone 3gs and began to turn it up, and up and up and at 60 it stopped and was no louder than my Iphone itself. I plugged back and forth between amp and Iphone and if there was any difference in volume it was slight.
Then I thought about earlier in the day when I was listening to the same iphone with my HD201's which are nowhere near 250ohms, yet had a similar level of volume as my DT880's. How is it possible for my 880's to be nearly as loud as a much lower impedance headphone? And how is it that my dedicated headphone amp is no louder than the stock amp in my Iphone? I'm not comparing quality, I need more listening tests for that but volume, the main reason I purchased it.
Do I just need to let it charge up more? What gives.
Also, when docked with the E9 I was shocked to find I have to unplug the 3.5mm input in order to hear the DAC, and with the USB cable plugged in, even with no E7, I suddenly get computer noise in my audio signal when amplifying analog sources. So now I have to unplug the USB cable when it's not in use too. I am thinking of sending the E7 back and just cabling my 24/96 USB Line 6 UX2 to it.....
I find the DT series of Beyers very easy to drive. Even the 600ohm versions can be amplified to more than listening volumes on devices that really shouldn't be able to do that. But they're just really efficient despite their impedance ratings. I've run 600ohm DT880's, DT990's and DT770's from the Fiio E10 for example and they all can be put to louder than listening levels on that little thing. I don't look at it's power output ratings, because it shouldn't be able to do that, technically, based on the measurements, yet it can. Then again, I've tested my HE-500 from the E10 and it too was able to get plenty loud on that thing. That makes no sense at all. At all. Yet there you go, numbers sometimes don't add up, but when you actually test the gear, it sometimes surprises you.
The E7 is not a very powerful amplifier. And newer apple devices are actually decent when it comes to power output (and DAC quality). So I think you're simply looking at that you added a similar level piece of source gear to a similar level piece of source gear and expected more when it's about the same. So your experience is the same. Kind of makes sense.
I would definitely send the E7 back, and get rid of the E9 too. I would suggest you use that money to play with amplifiers with much more power output, or simply higher potential voltages, like an OTL tube amp. You could look into the Schiit Magni, JDS Labs O2, a Little Dot MK II, etc.
If you need to keep it portable, I use a Fiio E11 with my higher impedance Beyers, and lower impedance Beyers (I have a lot of Beyers...), and it covers all of them just fine.