There is a very old thread [1] on alsa-user on this topic which seems to go through some yucky solutions. I have the same use case, and post some findings here.

Since pre-2003 alsa-lib calls wordexp(3) on the filenames. I am using the patch below in /usr/share/alsa/alsa.conf

It follows a precedent set by other files such as .Xdefaults-hostname.

I'd submit a patch, except there seems to be no guarantee that HOSTNAME is in the environment (on Slackware it is explicitly set in /etc/profile.) Without it I can only see a bash local variable.

From the old thread I imagine this function (or at least this mail) would

be useful to others.

Would it be better to patch the C code to provide a token (eg. '\h') that is substituted by the hostname? Or is it enough to assume that HOSTNAME would be set?

I didn't consider short vs. long hostnames, I suppose $HOSTNAME gives the user/admin some control over this.

This:

~/.asoundrc-$(hostname -s)

may work, but I don't see that forking a process is an option.

[1] http://thread.gmane.org/gmane.linux.alsa.user/27532/focus=27542