Finally, I created a WAV file that plays back!
I think the problem was:
1) I had not checked the little "rec" box under "line-in"
on the Gnome sound mixer ( or volume controller ).
2) I think there was a problem with impedence matching between
the sound card and the device I used to interface with it.
The adapters and chords I used to hook the two devices
( sound card to guitar amp or sound card to audio mixer)
were all good and the devices themselves worked fine,
as well as the sound card. Otherwise, why all I got was
an empty file that played nothing is still a mystery to me.
I finally got a usable WAV file by interfacing the sound card
with my ancient Fostex X-26 Multitrack tape recorder and using
its two audio line-out ( Left and Right) to plug into the Sound Blaster
Line's blue one-eight inch line-in using a Radio Shack adapter.
On the computer, in Gnome, I checked the little "rec" box next
to the line-in on the mixer, set the proper switches for volume
(Volume, PCM, IGain, Line-In, etc ), started a terminal, and used the
command: rec -v -r44100 -c2 -s -w input_file.wav
I did not record to tape. All I did was use the tape machine as
a small amplifier and ran the signal through it.
guitar->X-26 tape deck-> line-out ( audio plugs) ->
Radio Shack adapter -> one-eight inch blue line-in Sound Blaster Live
Then I had a lot of fun doing the Sox examples using the
input_file.wav. This is great!
