From the ALSA wiki
To get recording to work, make sure that the mixer control AD Input Select is set to off (muted).
You might also need to set the Mic +5V bias control to on using something like
$ amixer cset numid=43 on numid=43,iface=CARD,name='Mic +5V bias' ; type=BOOLEAN,access=rw---,values=1 : values=on $
The magic number '43' can be found from the output of
$ amixer controls numid=43,iface=CARD,name='Mic +5V bias' numid=42,iface=CARD,name='PCM 0 Output also on Line-In Jack' numid=3,iface=MIXER,name='Master Mono Playback Switch' ... $
For type CT4700, the one with 2 line-out jacks (green / black), you have to set number `42` control to on for enabling "hw:0,1" output on line1 and "hw:0,0" on _both_ line2 & line1.
Did this in my "/etc/asound.state", setting "value true" (SuSE9.3).
The (KMix) mixer setting "pcm0" (the leftmost) is for "hw:0,0" -> line1; so you can set "pcm0" to "0" for having one output exclusive for one DA-hw: 0,0->2 and 0,1->1
The mixer setting "pcm1" (2. left) sets level of "hw:0,1" -> line1.
I found no way so far to set level for "hw:0,0" output -> line2, is allway 100% (nor "hw:0,1" -> line2, allways 0%).
Only line1 has a onboard speaker-amp, which you can enable by jumper-setting. At line2, you have to use external amp or active speakers, you will not hear more than whisper even with headset.
Using "hw:0,1" for VoIP with internal amp and headphone on line1; and "hw:0,0" with active speaker on line2 works for me.
However, microphone is on "hw:0,0" only.