Every now and then I'm reminded I'm not the last emi2|6 or 6|2m user left in the world-- apparently Debian just recently made some of the changes that broke the eMagic drivers on other distros years ago and I've been getting mail about it again.
Background: The eMagic emi2|6 and 6|2m firmware loaders shipped with the Linux kernel have been broken for many years. Different distros have had them on life support with an inconsistent array of minor patches, but they've got a couple problems across the lot: races in the loader, an incorrect memory target, deadlocking all of USB with synchronous firmware requests in probe(), and the fact that the bitstream.fw file being shipped for the 6|2m is the wrong file. Apparently, someone accidentally substituted the 2|6 version of the file in a code cleanup years ago, and so even if you get the 6|2m loader to work, it crashes the device because it uploads the wrong thing.
Oh, and Linux is apparently shipping a buggy, early version of the firmware without 96kHz support. Even if you don't care about 96kHz for audio production, and you probably shouldn't, the extra frequency range makes these guys a lot more useful as software oscilloscopes.
I've maintained a working version of the driver with updated firmware for the past several years, but getting it into the official kernel always stalled on 'wait, do you have permission from eMagic to use this firmware?' Unfortunately a) Apple bought eMagic and discontinued all their hardware products more than a decade ago, b) to my knowledge, no one ever had explicit permission to use the firmware currently being shipped either. I have no real interest in having a battle over firmware licensing, so my fixes continue to be my own. If Apple turns out to care, I'll pull them down, but I doubt that will happen. I don't think Apple remembers this device even exists. Seriously, they're Bondi Blue. That's soooo late-90's.
Anyway, here's my latest, updated, out-of-kernel firmware loader with the last firmware release form eMagic. It works properly on 2.6.x and 3.x.x kernels for both the emi2|6 and emi6|2m. It replaces the old firmware and two kernel modules with new firmware and a single unified firmware loader module name emi.ko. All new! Such shiny. Wow.
If you have kernel module build dependencies installed, it should be as easy as untarring as root, make, and make install. I also included a 'make remove-old' target to clean out the old driver and avoid any conflicts. It just removes the old modules and firmware files; obviously that might make a packaging system a little pissy (and you'd probably have to re-run it on each kernel update).
tl;dr, get the driver here: http://people.xiph.org/~xiphmont/emagic/