Th UA-25EX (from Roland) is a USB 24 bit, 96kHz interface with MIDI. Incorporates 2 microphone preamps, compressor and limiter. The older UA-25 lacks the compressor.
This is regarded as one of the better USB interfaces due to the audio quality and support for higher bit rate/depth via dedicated drivers.
Is reported as fully working on Linux. In USB 1.1 class compliant mode it operates at 44.1kHz/16 bit. 'Advanced mode' supports up to 48kHz/24 bit (full duplex) or 96kHz/24 bit (half duplex). This is supported via a special driver that should be in all modern kernels, which also adds MIDI support.