first of all sound routing and drivers in Linux is a MESS !
hopefully this all will work itself out as an understandable standard some day
application have to be "aware" of or able to be configured to use the sound server/driver
there is a plugin for arts output in xmms
some people experience problems with this plugin -- i have never tried it
other people say it works great
yes i think you can try
and see if it will work (arts has bad latency problems)
arts is functional only if all you want it to do is play a sound when you do a gui thing and arts thankfully becomes a thing of the past in kde4
i might be wrong about this stuff but
my personal opinion -- since arts is really only doing software mixing and alsa does software mixing on it's own (not that well)-- and lots of modern sound cards can actually do hardware mixing ! -- i would just disable arts from starting in kde controll because it is inherently a drag on latency and a big drag on performance. i sort of look at it as a holdover from pre alsa days when there was no sound polling at all.
alsa is actually a sound server itself accepting both multiple kernel (driver) level clients and multiple user level clients and performing complex routing tasks. and also already mapps old code using oss devices to alsa devices. (again all of this doesn't work all that well)
can't use kde knotiffy gui sound event thingy then but who cares.
if you need a sound server look into jack -- it opens up new worlds of low latency posibilities.
or it is just a hack that bypasses all the cruft and blows past alsa for applications that are aware of it.
and makes thing even more confusing ???? anyway jack in my opinion actually works really well.