alsa.midi.info  110707 contact gnubien at #alsa on freenode.net
special thanks to thingol79 for providing this info.
use the quick start or first step info as needed;
quick start:
as sudo or root run:  modprobe snd_virmidi
if no errors from the modprobe command then
as user run this command: aplaymidi -l
choose 1 input and 1 output port for use then
as user run this command: aconnect <chosen-input-port-number>:0 <chosen-output-port-number>:0
if no errors then
as user run: fluidsnyth FluidR3GM.SF2
if no errors then
in another terminal in the directory where you have your .mid files
as user run this command: aplaymidi -p 128:0 <some .mid file>
if no errors then enjoy the sounds.
if there are errors or no sound read the first step section
first step: 
test to see if you have a midi capable soundcard;
lsmod |grep seq  #see if seq modules are already loaded or
modprobe snd-seq  #see if snd-seq module loads ok; then
run this command as sudo or root:  modprobe snd_virmidi
cat /proc/asound/oss/sndstat
example output: Synth devices: NOT ENABLED IN CONFIG  Midi devices:1: Virtual Raw MIDI
next: run this command: amidi -l  
example amidi -l output:
Dir Device    Name IO  hw:1,0    Virtual Raw MIDI (16 subdevices) IO  hw:1,1
Virtual Raw MIDI (16 subdevices) IO  hw:1,2
Virtual Raw MIDI (16 subdevices) IO  hw:1,3    Virtual Raw MIDI (16 subdevices)
if the above commands showed promising results
run: aconnect -i
example output:
client 0: 'System' [type=kernel]
    0 'Timer           '
    1 'Announce        '
client 20: 'Virtual Raw MIDI 1-0' [type=kernel]
    0 'VirMIDI 1-0     '
client 21: 'Virtual Raw MIDI 1-1' [type=kernel]
    0 'VirMIDI 1-1     '
client 22: 'Virtual Raw MIDI 1-2' [type=kernel]
    0 'VirMIDI 1-2     '
client 23: 'Virtual Raw MIDI 1-3' [type=kernel]
    0 'VirMIDI 1-3     '
run: aconnect -o                                                                                          
example output:
client 20: 'Virtual Raw MIDI 1-0' [type=kernel]
    0 'VirMIDI 1-0     '
client 21: 'Virtual Raw MIDI 1-1' [type=kernel]
    0 'VirMIDI 1-1     '
client 22: 'Virtual Raw MIDI 1-2' [type=kernel]
    0 'VirMIDI 1-2     '
client 23: 'Virtual Raw MIDI 1-3' [type=kernel]
    0 'VirMIDI 1-3     '

run this command:
aplaymidi -l
example output:
 Port    Client name                      Port name
 20:0    Virtual Raw MIDI 1-0             VirMIDI 1-0
 21:0    Virtual Raw MIDI 1-1             VirMIDI 1-1
 22:0    Virtual Raw MIDI 1-2             VirMIDI 1-2
 23:0    Virtual Raw MIDI 1-3             VirMIDI 1-3

Next choose the input and output ports you want aconnect to use;
from the above example outputs i choose input port 22 and
output port 23 and used this command: aconnect 22:0 23:0
run: aconnect input-port-number:number output-port-number:number
if no errors from that aconnect command then
Next you can connect some software synth (eg fluidsynth) to one of those virutal ports
your soundcard may need to load soundfonts for midi to work:
emu10k1 can read soundfont samples from the main memory on-the-fly using bus master DMA
emu10k1 loads soundfonts using asfxload from the awesfx package: see references
X-Fi has some onboard RAM, but I'm not sure how exactly it is used: currently just fyi
you can download some soundfonts here: http://hammersound.net/cgi-bin/soundlink.pl
check "Collections" and download some GM compatible one, like Fluid - Release 3 [68.5MB] or whatever 
soundfonts from the above site are compressed so you need to uncompress them;
http://melodymachine.com/  might have some info on uncompressing the soundfonts;
you can download the uncompressed soundfonts:      
http://melodymachine.com/
you can use timidity/fluidsynth to both load the soundfonts and play midi files
run: fluidsynth and type "load FluidR3 GM.SF2" to fluidsynth's command line
if you get an error run this command: mv FluidR3 GM.SF2 FluidR3GM.SF2
then check "aconnect -o" output, something like client 128: 'FLUID Synth (20766)' 
[type=user] 0 'Synth input port (20766:0)' should be there.
then run: aplaymidi -p 128:0 <some midi file>
free .mid file download site: http://www.mididb.com/
Tip: if you run fluidsynth without using aconnect to input and output ports
then fluidsynth will use alot more cpu % than with the aconnect command
references:
http://alsa.opensrc.org/MIDI
http://alsa.opensrc.org/PlayingMIDIFiles
http://alsa.opensrc.org/USBMidiDevices
http://www.tldp.org/HOWTO/MIDI-HOWTO-10.html
http://WWW.sabi.co.UK/Notes/linuxSoundALSA.html
http://www.alsa-project.org/~iwai/awedrv.html
http://twiki.org/cgi-bin/view/Wikilearn/LA_SoundFonts 
http://alsa.opensrc.org/index.php/SoundfontHandling 
http://alsa.opensrc.org/index.php/PlayingMIDIFiles 
http://alsa.opensrc.org/index.php/Sfxload http://alsa.opensrc.org/index.php/Asfxload
http://www.alsa-project.org/~iwai/alsa.html
http://wiki.archlinux.org/index.php/USB_Midi_Keyboards
http://wiki.archlinux.org/index.php/SB_Live!_Midi