Careful comparing headphone outputs, many PC audio sockets are still 100 Ohm output resistance.
It would be great if Creative would work with Ubuntu etc to get a stable driver. I just tried my old Audigy 2NX on Ubuntu 13.10 and got a crash report about too many sources
A friend of mine has Audigy 2NX and it didn't work for me on linux out of the box, despite having quite standard UAC1/UAC2 interface, so I set on figuring it out. It's been several years since then, but if I remember correctly, it had the same issue as Arcam rPAC -- if something tried to read its mixer levels, the card would "brick" until it was powered down. My guess is a firmware bug (based on weird behaviors of the rPAC).
Anyway, it can be worked around by preventing mixer read/set from happening, but not with PulseAudio, which does so implicitly. Unfortunately, it's not just udev or alsa scripts, newer kernels
touch mixer as well, so one has to either revert that commit or create a new "quirk" section for 2NX in sound/usb/mixer_quirks.c. Either way, building a custom kernel is probably necessary as Ubuntu doesn't build snd-usb-audio as a module.
So there's that. If you're a little "tech savvy" and want to explore things, you can make it work. Perhaps my crude kernel
patching tool for 13.04 could be used (it's built on the
official Ubuntu instructions for building a custom kernel).
In the end, I found the 2NX to be vastly underpowered in terms of headphone output, even the builtin Intel HD seemed to be better using AKG K240.
edit: As far as Creative goes, it doesn't surprise me. It always had poor driver support for SoundBlaster on Windows (and IIRC even on DOS) and extremely poor Windows driver support for the E-MU series.