From the ALSA wiki
This card uses the usb-audio driver and has functioned for some time with this driver as long as the advanced driver mode switch was off, limiting the card to 16bit 48kHz. Since Alsa 1.0.15 the advanced driver mode for this card has been supported however there is no information on how to use this mode.
Advanced Driver Mode Enabled
When in advanced driver mode the card appears to use a 3 byte sample
format. In order to capture audio data from the card while using the
advanced driver mode the following command is required:
arecord -r96000 -fS24_3LE -c2 -Dhw:0 ~/recording.wav (*)
(*)where the device (-D:hw0) and filename (\~/recording.wav) may be different for your system/preferences.
Retrieved from "http://alsa.opensrc.org/Edirol_UA-1EX"