So I bought an Apogee(tm) ONE(tm) USB interface because I felt that owning
5 audio interfaces wasn't quite enough;  It has a big volume knob on it,
but as it turns out, it doesn't work under Linux.  (conversely, my previous
main interface had a completely working set of volume knobs for everything)

So, for days I've been roughing it with alsamixer, but opening a goofy
ncurses interface to adjust my volume just doesn't feel right, and
using the master volume slider is less than ideal...  So
I've added a master volume knob to the transport that has zero effect
on the offline rendering volume.