Reference USB card driver?

[René Herman]

Good day.

I recently acquired a TerraTec DMX 6Fire USB card to play with, which
works after one/two just to alsa-devel sent out patches. Not very good
though; it's for example rare to not have my music skip when Pulseaudio
mixes in the "there's new mail" sound from Thunderbird.

I haven't been around here for a very long time now but have some
ALSA-experience with ISA and PCI hardware from long ago. None with USB
whatsoever though. Is there a reference/best-practices USB card driver
that I can/should look at?

Regards,
Rene