If the binaries aren't there something went wrong with the install from the zip file. I suggest you inspect the zip file and if it is damaged or incomplete download a fresh copy. Then copy the missing files from the zip to your Kindle. Here is a test output from the zip:
Code:
dhdurgee@A31524PT:~/Downloads$ unzip -t sox-0_2.zip
Archive: sox-0_2.zip
testing: music/ OK
testing: extensions/ OK
testing: extensions/sox/ OK
testing: extensions/sox/README.txt OK
testing: extensions/sox/bookmark.sh OK
testing: extensions/sox/config.xml OK
testing: extensions/sox/killsox.sh OK
testing: extensions/sox/library/ OK
testing: extensions/sox/library/libFLAC++.so.6 OK
testing: extensions/sox/library/libFLAC.so.8 OK
testing: extensions/sox/library/libgsm.so.1 OK
testing: extensions/sox/library/libid3tag.so.0 OK
testing: extensions/sox/library/libltdl.so.7 OK
testing: extensions/sox/library/libmad.so.0 OK
testing: extensions/sox/library/libmagic.so.1 OK
testing: extensions/sox/library/libmp3lame.so.0 OK
testing: extensions/sox/library/libpng12.so.0 OK
testing: extensions/sox/library/libsndfile.so.1 OK
testing: extensions/sox/library/libsox.so.2 OK
testing: extensions/sox/library/libsox_fmt_amr_nb.so OK
testing: extensions/sox/library/libsox_fmt_amr_wb.so OK
testing: extensions/sox/library/libsox_fmt_caf.so OK
testing: extensions/sox/library/libsox_fmt_fap.so OK
testing: extensions/sox/library/libsox_fmt_flac.so OK
testing: extensions/sox/library/libsox_fmt_gsm.so OK
testing: extensions/sox/library/libsox_fmt_lpc10.so OK
testing: extensions/sox/library/libsox_fmt_mat4.so OK
testing: extensions/sox/library/libsox_fmt_mat5.so OK
testing: extensions/sox/library/libsox_fmt_mp3.so OK
testing: extensions/sox/library/libsox_fmt_paf.so OK
testing: extensions/sox/library/libsox_fmt_pvf.so OK
testing: extensions/sox/library/libsox_fmt_sd2.so OK
testing: extensions/sox/library/libsox_fmt_sndfile.so OK
testing: extensions/sox/library/libsox_fmt_vorbis.so OK
testing: extensions/sox/library/libsox_fmt_w64.so OK
testing: extensions/sox/library/libsox_fmt_wavpack.so OK
testing: extensions/sox/library/libsox_fmt_xi.so OK
testing: extensions/sox/library/libtwolame.so.0 OK
testing: extensions/sox/library/libvorbis.so.0 OK
testing: extensions/sox/library/libvorbisenc.so.2 OK
testing: extensions/sox/library/libvorbisfile.so.3 OK
testing: extensions/sox/library/libwavpack.so.1 OK
testing: extensions/sox/menu.json OK
testing: extensions/sox/playall.sh OK
testing: extensions/sox/playfile.sh OK
testing: extensions/sox/playinternetradio.sh OK
testing: extensions/sox/silence.wav OK
testing: extensions/sox/sox OK
testing: extensions/sox/soxi OK
No errors detected in compressed data of sox-0_2.zip.
dhdurgee@A31524PT:~/Downloads$
Note that both sox and soxi are there as well as an entire library subdirectory.
Dave