Today I figured out some sndiod flags.  Actually, I had been
shooting  myself in the foot somehow trying to run sndiod in
-ddd  ebugmode.   sndiod is the openbsd  intermediate  sound
device wrangler.  My desire is to use sndio's mon rec device
to  let  me  record   all system   sounds   together   in  a
what-you-hear-is-what-you-get  kind of way.  I set the flags
of sndiod as follows. 

rcctl   set   sndiod   flags  -f   rsnd/0   -F   rsnd/1    \
 -s default -m play,mon -s mon

When  I  was  spitballing  earlier,  I just did -m  mon  not
play,mon. Eh, it works. 

rcctl restart sndiod

<anonradio playing>

aucat -f snd/mon -o anonradio.wav

Whence  I can just produce sounds,  hopefully  deliberately,
and  record  them in sum from that device.   As we speak,  a
round  of synth battle royale is beginning.  In my dreams  I
will get into the next one.  (And then I can start  worrying
about  how  to begin producing   sounds  (printf   \"\a\"...
rhythmically)). 

After which the only technical challenge  is finding out how
to icecast2 to anonradio (and prostrating  myself before the
council  of encumbent  DJs).  I see net/ices  in the openbsd
ports, perl script mp3 source for icecast/2. 

The nontechnical  challenge I am imagining is to try writing
some   simf   DSL and run it from  the repl,   or  otherwise
building an SDL2 gui from which to use sdl2-mixer  (if I use
a  bunch  of mp3s or something).   I'm not sure  about   m3u
playlist item communication. Geeettting somewhere.