Pros: Powers the HD650, Sounds Great
Bought this AMP to power my HD650 and to enable me to dock my E7 which I had prior to purchasing this. It provides plenty of power for HD650, and sounds very good. Bass seems to be improved a lot and soundstage has improved slightly.
For a budget amp to power high impedance cans, I recommend it.
E7 works very well with the E09K
If you have an E7 and are thinking of purchasing this, buy NEW. The E09K's manufactured before October 2012 do not support the E7 (there is a problem with hissing). This doesn't apply to the E07K.
The only drawback? Now I have a taste of what HD650's can really do with a high powered AMP and I want more :)
Hope this helped.