The Hifi-M8 is definitely a portable device, just not "pocket-sized". I think there's a small distinction there.
When I personally say "portable" I don't mean "pocket-sized" which this clearly is not. However, the device (and I CAN'T WAIT guys!!) maybe just a bit bigger than, say, my ALO International head-amp/DAC, but it's the same size, w/ iDevice, as my ALO RxMK3-B, which I've taken everywhere from Hawaii to Denver to Chicago and New York! While it may not be the size of your smartphone - it's still totally portable.
Like the rig I just took to the LAOC Audio Society event last Sunday:
Astell&Kern AK100 player
ALO International head-amp
Audeze LCD3's (w/ ALO Green Line cables)
That may not sound too portable, but imagine the reactions from old school audiophiles when I showed up with it! One of them is pictured below (my buddy Russ, who's a live sound engineer and audiophile - and was BLOWN AWAY at the resolving capabilities and "goose-bump factor" of the system). Many of us have such small devices we might look at the HiFi-M8 as a large item. As somebody who's been reporting on high end audio for 20 years (man that makes me sound old, when I'm only 38) I can say all these items are portable next to some of the larger components! It's refreshing to have such amazing sound on-the-go now.
I don't feel like I'm missing anything w/ my portable rig,
and I've been using the E.A.R HP4 tube headphone amp + SimAudio Moon DAC100 as my reference at home lately! WHOAH. Review on that to come ASAP.
In the meantime - I'm just excited to see you guys push the envelope of whats possible in portable today! I know Michael and his team will hit it out of the park on this one...