let me say this...
e3... makes everything worse than the original...
e5... no difference in good, that if it doesn't make everything worse....
e7... is good, pretty good, verry good compared to it's brothers....
e11.... next generation amplifier....
want until e11 is out, about march.... e7 is a usb dac, it;s meant to be used as usb dac, not headphones amplifier.,.. it's great as headphonesc aplifier, but not the same deal as it is as usb dac.... u should't buy it only for headphones....
e11 will have a much more higher wuality for headphone amplifying, and will be cheaper than e7... you decide....
and about what you were saying.... e7 is an usb dac... it does not just have this.... the headphone amplifier for it is e7+e9, wich is desktop headphone amplifier... e7 alone makes a good job, but it's not that stellar.... it may improve, but not dramatic.....