Are the drivers in the current alsa-drivers package exactly the same as those in the current Arch kernel? Or are there any slight differences - for example, a patched via82xx driver that lets you adjust the master and PCM volume?
You can find what alsa version is compiled into kernel by running:
cat /proc/asound/version Advanced Linux Sound Architecture Driver Version 1.0.8 (Thu Jan 13 09:39:32 2005 UTC).
Current alsa-driver package version is:
pacman -Ss alsa-driver current/alsa-driver 1.0.8-3 An alternative implementation of Linux sound support
You can find if there are any patches applied in alsa-driver package by reading /var/abs/multimedia/alsa-driver/PKGBUILD. If kernel package also doesn't apply any patches to via driver I guess they should be exactly the same (though drivers from alsa-driver package are for 2.4 kernels only).
It's possible to update alsa and recompile kernel - there are howtos on alsa project and alsa wiki sites.
This is probably not the information you expected :-)
You could give more info on your kernel version and soundcard (model, lspci, etc). I don't have this kind of hardware but it seems that volume problem is connected with dxs and modinfo snd-via82xx seems to support additional parameters in current driver. I've seen some info how to set it up on the alsa sites and google.
Ahh.. So perhaps I should disable dxs (dxs_support=2)?