Sorry for the long time in replying.
Copy this to a file name ".asoundrc" and place it in your home directory:
Code:
# Personal: ~/.asoundrc
# Global: /etc/asound.conf
pcm.snd_card {
type hw
card 0
device 0
# mmap_emulation true # If mmap() err
}
pcm.dmixed {
type dmix
ipc_key 1024
#ipc_key_add_uid false # No user restriction
#ipc_perm 0666 # IPC permissions for multi-user
slave {
pcm "snd_card"
#rate 48000 # If chipmunks
#buffer_size 4096 # If pops
#period_size 512 # If crackles
}
}
pcm.dsnooped {
type dsnoop
ipc_key 2048
slave {
pcm "snd_card"
#rate 48000 # If chipmunks
#period_size 128 # If crackles
}
}
pcm.softvol {
type softvol
slave.pcm "dmixed"
control {
name "Software" # Can rename this
card 0
}
}
pcm.duplex {
type asym
playback.pcm "plug:softvol"
capture.pcm "plug:dsnooped"
}
pcm.!default {
type plug
slave.pcm "duplex"
}
pcm.dsp0 {
type plug
slave.pcm "duplex"
}
You will need to access your audio device one time, before the new "Software" control will appear in you mixer. If you have no "Master" volume control (you said you didn't), then you can rename it that - and voila.
There are some commented items, but they should be self explanatory enough. I used mainly documentation on the ALSA website, and yes it can be difficult to wrap your head around 
Anyway, let me know if that doesn't work (I'd be surprised, but I suppose it's not impossible).