Used the E7 / E9 combo with the 650's for a few months. It sounds just fine, you shouldn't have any problems. The HD650 was a significant upgrade over the Shure 840's, both being run from the E7 / E9, if that gives you any indication or what to expect.
That being said, I really don't use the E7 / E9 anymore since upgrading, but that was kind of the point. If you decide later to upgrade then its a fairly low cost temporary solution that does just fine.
Edited by barid - 12/7/12 at 12:18am