ok i will accept your response even though i don't understand it and try to answer.
you didn't say what kind of sound card but if your soundcard cannot load it's own soundbank then the most common way to playback midi is with a software synthesizer (TiMidity++) timidity is essentially a midi to wave converter
but to you question if your soundcards gameport is supported by alsa as a midi port (snd_mpu401_uart)
then yes you can input or output midi through the gameport
use the command "pmidi" to see what's up
here is mine
(gary) ~ $ pmidi -l
Port Client name Port name
64:0 EMU10K1 MPU-401 (UART) - Rawmi EMU10K1 MPU-401 (UART)
65:0 Emu10k1 WaveTable Emu10k1 Port 0
65:1 Emu10k1 WaveTable Emu10k1 Port 1
65:2 Emu10k1 WaveTable Emu10k1 Port 2
65:3 Emu10k1 WaveTable Emu10k1 Port 3
and lsmod /modprobe will help you load the module if it's not loaded
alsa also contains a command line utility for complex midi connections called "aconnect" there is a kde version "kaconnect"
that's about all i can say without more particular information