To convert .mid (or .kar) to PCM WAV (or encode to other format) you can use
the Bass plugin bass_midi.dll, but need a Soundfont (.sf2) to work.

WARNING: The output is 32 bit float but with many values over 0 dB, then
always Normalize the output at your desired level.

Reading the bassmidi.txt:

"SF2 soundfonts are used to provide the sounds. There are several soundfonts
available on the internet. One example (Chorium) is available from the BASS webpage.
On Windows, the Creative 28MB (28MBGM.SF2), 8MB (CT8MGM.SF2), 4MB (CT4MGM.SF2),
or 2MB (CT2MGM.SF2) soundfont will be used by default when present in the Windows
system directory. SFZ soundfonts are also supported."

But any Soundfont renamed to one of these fonts, for instance 28MBGM.SF2, are
used by bass_midi.dll automatically. Then you can have several Soundfont's and
copy them to the System Directory\28MBGM.SF2 to test different output.

You can download a couple of Soundfonts from:
http://www.un4seen.com/download.php?x/ChoriumRevA
http://www.un4seen.com/download.php?x/WeedsGM3

But there are many, and better, to download, I found:

 32.461.770 32MbGMStereo.sf2
155.405.818 Arachno SoundFont - Version 1.0.sf2
 34.117.830 bennetng_AnotherGS_v2-1_XG.sf2
 34.137.506 bennetng_AnotherGS_v2-3_GM_GS.sf2
  5.724.684 Casio VL-1.SF2
 12.189.088 Chaos_V20.sf2
 28.926.744 ChoriumRevA.SF2
242.522.418 CrisisGeneralMidi1.8.sf2
  2.167.684 Ct2mgm.sf2
  4.174.814 Ct4mgm.sf2
  7.572.224 Ct8mgm.sf2
148.358.590 FluidR3_GM.SF2
 31.281.184 GeneralUser GS v1.47.sf2
278.600.888 OmegaGMGS2.sf2
105.991.124 RealFont_2_1.SF2
272.620.582 SF2015.sf2
247.406.594 SGM-V2.01.sf2
371.375.172 Timbres Of Heaven GM_GS_XG_SFX V 3.2 Final.sf2
231.607.820 Titanic_200_GMGS_1.1.sf2
 54.894.076 WeedsGM3.sf2

For instance you can free download another from:
http://www.omegagmgs2.com/

I make a little util than, placed at same folder than .sf2's, for instance
here, can help you to select and copy the desired file: 0-CopySf2.exe
