Since I have been looking at mobile solutions, there seems to be a common problem of how to get your data/music to your fancy new USBs etc.. People especially want to use their fancy new portable USB DACs (Firefly, Meredian Explorer, ALO Island, LH Geek Out, etc.) with their iDevices or Android devices. Typically, your USB DACs do not work with your iDevices/Android/portable devices for TWO reasons:
Driver needed: Luckily most of the newer USB DACs are compliant with newer USB standards that basically makes this problem disappear. Just check to see if your USB DAC is "driveless." So if you have newer iDevice/Android etc. and newer USB DAC, this problem should not exist for you.
Of course, with iDevices, there is a related problem that there is no USB socket to plug that shiny new USB DAC. The solution here is to get Apple CCK for older ipod/ipad models and/or Lighting to USB adapter.
POWER POWER POWER: Basically, iDevices and many Android devices do not provide power through their USB or USB like port (30 Pin Apple, Lightning, etc.) to run a USB DAC.
What you quickly discover if you put a powered USB HUB between your iDevice/Android/etc. and your USB DAC, everything suddenly works. The problem is that your USB HUB needs to be plugged into outlet which kind of defeats the whole idea being mobile even though it is probably work for you if you camp out in Starbucks all day.
To solve this problem, I have seen random hacked together solutions including creating battery packs etc.
What we need is a battery operated powered USB HUB. There was one that has been cited on this website:
Problem is that it seems like it doesn't work very well (based on the reviews) and, even worse, the product isn't even manufactured anymore so availability is limited.
However I have found a better battery operated powered USB HUB to rule them all:
Good reviews and I can personally certify it is working with even power hungry USB Drives. But beyond giving you a truly portable powered USB HUB, it does so much more. It does things similar to Seagate's Wireless Drive that others have been talking about. However with this device, you have similar functionality to the Seagate but with much more flexibility such as using USB memory sticks as drives, etc.
Hope that helps.