Sound configuration for using microphone from Realtek HDA and sound output from usb sound card. Also using alsa downmixing and input/output sharing.

.asoundrc

# high quality resampling
defaults.pcm.rate_converter "samplerate_best"

# alsa fix to play many sounds
pcm.output {
        type asym
        playback.pcm {
                type dmix
                ipc_key 5678293
                ipc_perm 0660
                ipc_gid audio
                slave {
                        channels 2
                        pcm {
                                format S16_LE
                                rate 44100
                                type hw
                                card 2
                                device 0
                        }
                        period_size 1024
                        buffer_size 8192
                }
                bindings {
                        0 0
                        1 1
                }
        }
}
# alsa fix to record many sounds
pcm.input {
	type dsnoop
	ipc_key 1027
	slave {
		pcm "hw:0,0" 
		channels 2
	}
}
# set default inputs and outputs
pcm.!default {
	type asym
	playback.pcm {
		type plug
		slave.pcm "output"
	}
	capture.pcm {
		type plug
		slave.pcm "input"
	}
}
# downmixing
pcm.!surround51 {
	type vdownmix
	slave.pcm "output"
}
pcm.!surround40 {
	type vdownmix
	slave.pcm "output"
}