Lohb
Headphoneus Supremus
Sure, though what would you change after? an amp (portable?) in between or another source entirely? I just want something that's portable enough to move around the house fairly easily...Will probably get some IEM's as well for out and about.
knorris908 point about the portas is good - I'm presuming the harder to drive phones will be quite a bit heavier on the battery....
iBASSO PB2 portable amp (LME49990 4x Opamp / dummy buffer kit) transportable stack