One thing I've been using a lot recently for large volumes of files is
the --omacro:XXX=YYY flag. This is quite hand because you can use a
simple Unix shell script (or .bat file) to pass lists of filenames to
Csound to processing.

You can take the below example and choose to use NO <CsOptions> but do
something like

for var in `ls *.wav`
do
csound -o/newdir/$var --omacro:SOUNDFILE=$var -d
done

You can also use --omacro in your <CsOptions> or commandline to define
macros so you could have something like this. You may find this useful
if using Python or otherwise communicating with Csound using externals
means suits you.

<CsoundSynthesizer>
<CsOptions>
--omacro:SOUNDFILE=test.wav -odac -d -+rtaudio=whatever
</CsOptions>
<CsInstruments>

sr = 44100
ksmps = 1
nchnls = 2

instr 1
  al, ar diskin2 $SOUNDFILE, 1, 0, 1
 outs al, ar
endin
</CsInstruments>
<CsScore>
i1 0 100
e
</CsScore>
</CsoundSynthesizer>


-David