I honestly use the HRT and P4 as a desktop in the office with closed headphones to drive away distractions.....and do not travel with this set up, though I am inspired to. My travel rig is the PA2V2 or E17 and earbuds, depends if I want to go retro, or feel good about the build-quality tactile feel of the FiiO.
At home, when I want to switch rooms.....I drive this rig through my DT770 PRO 80 OHMs, which I have come to appreciate even more having later bought the KRK 8400s (piercingly harsh treble.)
So, I have the range I want, enough detail, separation..... soundstage could be wider (I suspect that is a factor of the phones, though) the HRT unlifts a veil from the iPod Touch, which has a good internal DAC itself. My next headphone will be a more airy open circumaural for a wider and frontal stage.
I am envious of the new Leckerton owners.... I am just too tied to the Apple eco-system to be able to use many other DACs out there.