Update: This patch is now a part of the ALSA project in releases 1.0.15 or above, and Linux kernel 2.6.24 and above.
The Final Scratch v1 audio interface is a pair of standard USB 1 audio devices connected to a hub, which attempts to hide itself from the OS as 'vendor-specific'. It consists of two independent stereo full-duplex audio interfaces with built-in phono preamps, making it a good audio interface for use with xwax.
On Linux kernels up to around 2.6.17, a bug in the USB drivers means the device is detected and works fully using the snd-usb-audio module. On later kernels, Linux behaves correctly and the ALSA driver needs a small patch to force the interface to be detected.
In the ALSA source, patch the file alsa-kernel/usb/usbquirks.h to include the lines
/* Stanton/N2IT Final Scratch v1 device ('Scratchamp') */
{
USB_DEVICE(0x103d, 0x0100)
},
{
USB_DEVICE(0x103d, 0x0101)
},
and then recompile and reload the modules.
Whilst the interface is good and very portable, the analogue side isn't quite so great. A quick search of the 'net will reveal all, including various hints and tips for improving the sound. Once you have it working, you will fully appreciate the irony of DJing using a pair of Serato vinyls, with a Final Scratch audio interface!
Note: The ScratchAmp can be used with Linux, but xwax doesn't support Final Scratch vinyls, and Serato vinyls are recommended instead