Thumb drive complications
As Jason from NY said, A&H only supports 16-bit recording on a thumb drive. 24-bit works fine on a USB hard drive I had that was 5 years old. But I really wanted to do 44.1 x 24-bit recording to a thumb drive to make this "no moving parts" all the way. I bought a Kingston Data Traveler Ultimate thumb drive, which is on A&H's approved products list (for running 16-bits). This thumb drive is way faster (sustainable write speed) than any of my old USB hard drives, so I was puzzled why the hard drive can run 24-bit and the flash drive could only do 16. But true enough, with the default formatting, trying to run the Kingston results in occasional dropouts.
Long story short, I got it to work using this procedure:
1) Format the Kingston drive in the ICE16 -- see the manual. It will come up as "LO" (i.e. 16 bit). That will create a couple of empty folders and an INI file.
2) Take the Kingston to your PC and copy the folder structure and INI file temporarily to your hard disk.
3) From the PC, format the Kingston as FAT32, but specify the allocation unit size as 64KB (don't use the default which is 32KB).
4) Then copy the folder structure back only the Kingston.
5) Still on the PC, go into the file named recorder.ini and change the samplewidth=16 line to read samplewidth=24. Then eject the Kingston from your PC.
Plug it into the ICE and it will come up as "HI" (i.e. 24 bits.) With this format, I have never had a single dropout. It works great for me. A&H does not support that, so you are on your own, but this is how I plan to run always.
On a related note, be aware that if you want to run 88.2 or 96, it will only record on 8 channels (regardless of whether you use a hard disk or thumb drive,) but you can do 16 channels at 48K x 24 bits.
The unit is fabulous. Much less heartburn than trying to get a *#$%^&%^& DAW to record reliably in the field.