It must be no shared irq for the sound card even at the PIC level.
http://www.gentoo.org/doc/en/articles/hardware-stability-p2.xml
My sound card is not sharing an IRQ; I made sure of this when I set up my system, and I just double-checked.
You
can compare too the output of "lspci -v" and "lsmod". You must have
only the modules corresponding to your harware. It can append if you
have more modules as needed with the kernel at, at boot time, the
kernel load concurrent modules for the same hardware (specialy the
chipset). It is more an issue with distribution kernel as with a
specific kernel as with gentoo.
I have a meticulously configured kernel with only the essential modules and built-in support that I need.
I
get better result with the realtime-lsm as with pam, and it is the
recommanded way if you want to do heavy audio work. If you take a look
at audio distribution as agnula or planet ccrma, that is the way they
work.
I'm currently using only PAM rlimits (I don't have realtime-lsm
installed), but I may try what you suggest and switch to realtime-lsm
instead. I had worse luck with realtime-lsm in the past (we
discussed this via PM on the Gentoo forums), but I have since rebuilt
my whole system and done a few things differently, so perhaps it will
work better now.
Thanks,
Colin