I was recently given a Native Instruments Audio2 DJ interface, this is a great little card with working Linux drivers that works well with MIXXX using a variation of the .asoundrc available on the MIXXX site and other locations.
But either my version of the card, or the Linux driver has changed, as my card identifies differently so the config files available elsewhere don’t work with my OS (Xubuntu 14.04 with kernel 4.2.0-18-lowlatency).