🚀 go-pugleaf

If you are planning on using the Signetics chip, might I suggest that
instead of simply using the peak input voltage to control the gain 
cell, you might look into using a real RMS detector chip as in the
dBX noise reduction scheme.  This setup would be a bit more tricky to
design, but would be superior to simply using the peak voltage--
your gain tracking would be more accurate.

I believe that NEC makes just such an item, intended to be used in
a dBX type NR setup.  I think that you might find this chip in the
"Linear Circuits for Audio System" (sic) databook.  I have no idea
as to the availability of this device.  Call a distributor and ask
for a sample...

As for your actual compression range, I imagine that you would be
looking at a maximium ratio of 2:1 or so.  Any more would begin to
sound really funky.  As with any compressor, noise pumping might
become a problem--although with CD source material, this will most
likely be kept to a minimum.