MOTM

> These big 10V P-P signals need to be attenuated down. don't they?
> Should I do that with a VCA, or a mixer module, or some special module,
> or with outboard equipment?

The short answer to your question is MOTM-890, the long answer is much 
more interesting.

Since you're a computer guy: google up a few pages on "+4dBu", line level 
and "-10dBu" consumer level. There's also instrument level and mic level. 
Important things in an audio connection: impedance,  voltage, balance.

I did some quick searching and found:
   http://home1.pacific.net.sg/~firehzrd/audio/signals.html

> Sorry if this is boring to everyone else!

We all start at the beginning ;)

--mikes